Syntax error invalid syntax python pip

The pip package installer is only available from the command line. You’ll get the SyntaxError: invalid syntax error if you try to install a package via the Python interpreter or a Python program. When beginners try to install Python packages, one of the most common issues they see is SyntaxError: invalid syntax. We will examine a real-world scenario to demonstrate the issue at hand.

The command prompt area is where we run Python to launch the Python shell, but within it is a shell. How can we tell if we’re in the Python shell or the command prompt? We can simply confirm it.

When we execute the Python shell with the python command, we are in the Python shell, and three greater than signs will appear in the left corner. These three indicators indicate that the user is working in a different shell, in this case, the Python shell. Another method for newbies to recognize whether they are within the command prompt is to look for a drive name and a path name of your folder where your cursor blinks.

In this “PIP install Invalid Syntax” post, we will explore what causes the pip install improper syntax problem and what it means. We’ll review an example of this problem to show you how to correct it in your code.

What exactly is PIP?

PIP is a Python package installer. It lets you download, install, update, and uninstall software programs. Further, pip is usually installed by default on your system.

It’s important to understand that pip is a command-line utility, not a Python module. It will assist you in comprehending why this mistake arises and how to resolve it.

pip install invalid syntax

Python pip is a package installer written in Python. The pip tool allows you to download and install packages from the Python Package Index, which contains thousands of libraries with which you can work with your code.

The pip package manager has its command line interface. pip is not part of your Python installation. It is because pip is an installer rather than a program executing code.

In case these tools were bundled together, it would be more difficult for developers to install packages because the syntax used to start a Python application would also be used to install modules. It is a regular occurrence in programming environments. To install packages, Node.js uses npm. The latter node command is required to launch Node.js software.

What causes the “pip install invalid syntax” error?

When you try to call the pip command from within a Python interpreter or script, you get the “pip install invalid syntax” error. As previously stated, pip is a command-line utility for managing Python packages. You cannot, however, try to access it directly from a Python interpreter.

It’s the same as typing ls -la into the Python interpreter. As a result, the next steps will be geared towards reproducing this problem. Assume we wish to install the idna package with pip. Begin by launching the Python interpreter as:

tuts@codeunderscored:~$ python3

It should provide us with a Python environment that is interactive. When we perform the pip install idna command in the session, we get the following error:

As we can see, we can’t use pip to install a package inside a Python interpreter.

What is the fix?

The solution is straightforward. Use the pip install command from a terminal window rather than the Python interpreter. Exit the Python interpreter session before installing the idna package with pip:

tuts@codeunderscored:~$ exit()

Once you’ve returned to your system’s shell, type:

tuts@codeunderscored:~$ pip3 install idna

Replace “idna” with the target package you want to install. The problem should be fixed, and your target package should be installed.

Example problem with Beautiful soup four library

In this section, we will install the Beautiful Soup 4 library (bs4) in a development environment. This library allows you to scrape a web page and obtain specific data. To begin, launch a Python 3 shell. We’ll complete all of our project work in this shell:

tuts@codeunderscored:~$ python3

An interactive shell is launched, where we can enter our Python code.

Next, we’ll include the bs4 library in our code. Any external libraries we want to use must be imported before they can be used in a program or the shell. The following command will be used to import the bs4package:

from bs4 import BeautifulSoup

When we try to import our package, our code throws a ModuleNotFoundError. It implies we won’t be able to continue working on our program. Python is unable to discover the package modules required to write our program. Let’s resolve this issue by installing the bs4 library while still in the Python interactive interface as follows:

This command generates another error:

"SyntaxError: invalid syntax"

The pip command in the Python shell cannot be used to install bs4. By the way, the package installer for Python 3 packages is pip3.

The cause is that we attempted to use the Python interpreter to install the bs4 package. You can tell since we launched Python 3 with the python3 command and ran the pip3 install command. The reason for the latter is pip is not a Python keyword, so Python produces a pip install invalid syntax error. pip is a command-line utility that must be executed from a command-line shell.

To resolve this issue, we must first exit our Python shell:

tuts@codeunderscored:~$ exit()

The exit() instruction instructs Python to close the currently open interpreter. Then, using the command prompt, we can install bs4 as follows:

tuts@codeunderscored:~$ pip3 install bs4

This program will download and install the pip library on our system. After this command has been executed, we may launch a new Python shell:

tuts@codeunderscored:~$ python3

The bs4 library should be accessible to our new shell. As a result, we can put this to the test by importing bs4 into our code:

from bs4 import BeautifulSoup

There is no error. It indicates that the import was a success. Go ahead and now incorporate bs4 into your program.

Conclusion

When beginners try to install Python packages, one of the most common issues they see is SyntaxError: invalid syntax. In this article, we have examined two real-world scenarios to demonstrate the issue.

Congratulations! We discovered the cause of the “pip install improper syntax error” and how to fix it in this post.

We will learn, with this explanation, why we get an invalid syntax error when we try to install Python packages. We will also learn how to fix this error in Python.

Use the pip Command Without Getting an Invalid Syntax Error in Python

Many errors exist in Python, but one of the most common that beginners face is SyntaxError: invalid syntax when they try to install Python packages. Let’s get started with a real example to show you the error.

When we tried to install the Python package inside the Python shell, we got the Syntax Error.

Sometimes, beginners do not understand what they did wrong. You may be a little confused about working with the Python shell if you are a beginner.

To better understand, if we type exit inside the Python shell, it will not work. We often use the exit command in the command prompt, but it is not working this time because the same command will not work in the Python shell.

Looking at the very top corner, you can see the Microsoft command prompt that ensures you are working in the command prompt. As a beginner, it sometimes becomes confusing; however, if you type exit, you will get an error Use exit() or Ctrl-Z plus Return to exit.

We get this error because we are running a terminal command to exit from this Python shell, which will not terminate the Python shell. The exit command will terminate our command prompt window when we run inside the command prompt area.

The command prompt area lies where we run Python to start the Python shell, but inside it, the area is a shell. How do we know we are in the Python shell or the command prompt? Well, we can verify it easily.

When we run the Python shell using the python command, we are in the Python shell, and after running the Python shell, three greater than signs will show in the left corner. These three signs signal that the user is working in a different shell, the Python shell in this case.

In the Python shell, you will need to enter different commands that should be related to Python, where this pip command fails. You would think that this particular pip installation command is related to Python, so it must work inside a Python shell.

Another tip for beginners to recognize they are inside the command prompt is if you see a drive name and a path name of your folder where your cursor blinks, then you are working in your command prompt.

If we run the pip command from our command prompt shell, we will not get an error, and now we can see Requirement already satisfied, which means the Flask is already installed in our system.

The pip package installer must be run from the command line. If you try to install a package from the Python interpreter or in a Python program, you’ll encounter the SyntaxError: invalid syntax error.

In this guide, we’re going to discuss the cause of the pip install invalid syntax error and what it means. We’ll walk through an example of this error so you can learn how to fix it in your code.

pip install invalid syntax

Python pip is a package installer. The pip tool lets you download and install packages from the Python Package Index, where thousands of libraries are available with which you can work in your code.

The pip tool runs as its own command line interface. pip is separate from your installation of Python. This is because pip is an installer rather than a tool that executes code.

If these tools were bundled together, it would be more confusing for developers who want to install packages because similar syntax used to start a Python program would also apply to installing modules.

This behavior is common across programming environments. Node.js relies on npm to install packages. To run a program using Node.js, you need to use the node command.

An Example Scenario

We’re going to set up the Beautiful Soup 4 library (bs4) in a development environment. This library lets you scrape a web page and retrieve particular pieces of data.

To start, let’s open up a Python 3 shell. In this shell, we’ll do all the work for our project:

python3


An interactive shell is opened in which we can write our Python code:

Python 3.8.5 (v3.8.5:580fbb018f, Jul 20 2020, 12:11:27)
[Clang 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>

Next, let’s import the bs4 library into our code. We must import any external libraries that we want to use before we can reference them in a program or the shell. Here’s the command we’ll use to import the bs4package:

>>> from bs4 import BeautifulSoup
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'bs4'

Our code returns a ModuleNotFoundError when we try to import our package. This means that we can’t continue writing our program. Python cannot locate the package modules that we need to write our program. Let’s fix this error by installing the bs4 library:

>>> pip install bs4


This command results in another error:

File "<stdin>", line 1
	pip3 install bs4
    	^
SyntaxError: invalid syntax

It appears as if we cannot install bs4 using the pip3 command in the Python shell. pip3 is the package installer for Python 3 packages.

The Solution

We’ve tried to install the bs4 package from the Python interpreter.

You can tell because we’ve opened Python 3 using the python3 command and then we’ve executed the pip3 install command.

Python returns a pip install invalid syntax error because pip is not a keyword in Python. pip is a command line tool that must be run from a command line shell.

To fix this error, we must first exit our Python shell:

>>> exit()


The exit() command tells Python to close the interpreter that is open. Next, we can install bs4 from the command prompt:

pip3 install bs4


This command will install the pip library onto our system. Once this command has executed, we can open up a new Python shell:

python3 


Our new shell should have access to the bs4 library. We can test this by importing bs4 into our code:

>>> from bs4 import BeautifulSoup
>>> 

No error is raised. This means that the import was successful. We can now use bs4 in our program.

Conclusion

The pip install invalid syntax error is raised when you try to install a Python package from the interpreter. To fix this error, exit your interpreter and run the pip install command from a command line shell.

Now you have the expertise you need to solve this error like a professional coder!

When i installed in python 2.7.6 i got the following error and i downloaded get-pip.py version 2.6

Collecting pip<10
c:userspadali1appdatalocaltemptmpet4gmlpip.zippip_vendorurllib3utilssl_.py:339: SNIMissingWarning: An HTTPS request has been made, but the SNI (Subject Name Indication) extension to TLS is not available on this platform. This may cause the server to present an incorrect TLS certificate, which can cause validation failures. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
c:userspadali1appdatalocaltemptmpet4gmlpip.zippip_vendorurllib3utilssl_.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by ‘SSLError(SSLError(1, ‘ssl.c:507: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version’),)’: /simple/pip/
c:userspadali~1appdatalocaltemptmpet4gmlpip.zippip_vendorurllib3utilssl.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by ‘SSLError(SSLError(1, ‘ssl.c:507: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version’),)’: /simple/pip/
c:userspadali~1appdatalocaltemptmpet4gmlpip.zippip_vendorurllib3utilssl.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by ‘SSLError(SSLError(1, ‘ssl.c:507: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version’),)’: /simple/pip/
c:userspadali~1appdatalocaltemptmpet4gmlpip.zippip_vendorurllib3utilssl.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by ‘SSLError(SSLError(1, ‘ssl.c:507: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version’),)’: /simple/pip/
c:userspadali~1appdatalocaltemptmpet4gmlpip.zippip_vendorurllib3utilssl.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by ‘SSLError(SSLError(1, ‘ssl.c:507: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version’),)’: /simple/pip/
c:userspadali~1appdatalocaltemptmpet4gmlpip.zippip_vendorurllib3utilssl.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
Could not fetch URL https://pypi.python.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host=’pypi.python.org’, port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError(SSLError(1, ‘_ssl.c:507: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version’),)) — skipping
Could not find a version that satisfies the requirement pip<10 (from versions: )
No matching distribution found for pip<10

It’s a sadly unhelpful error message and it’s one that you’ll see quite often when learning Python.

What does SyntaxError: invalid syntax mean?
What is Python trying to tell you with this error and how can you fix your code to make Python happy?

What is a SyntaxError in Python?

This is Python’s way of saying «I don’t understand you».
Python knows that what you’ve typed isn’t valid Python code but it’s not sure what advice to give you.

When you’re lucky, your SyntaxError will have some helpful advice in it:

$ python3 greet.py
  File "/home/trey/greet.py", line 10
    if name == "Trey"
                     ^
SyntaxError: expected ':'

But if you’re unlucky, you’ll see the message invalid syntax with nothing more:

$ python3.9 greet.py
  File "/home/trey/greet.py", line 4
    name
    ^
SyntaxError: invalid syntax

This error message gives us no hints as to what might be going on outside of a line number and a bit of highlighting indicating where Python thinks the error occurred.

Causes of SyntaxError: invalid syntax

What are the likely causes of this mysterious error message?

When my Python students hit this error, the most likely causes are typically:

1. Missing a colon (:) at the end of a line or mixing up other symbols
2. Missing opening or closing parentheses ((…)), brackets ([…]), braces ({…}), or quotes ("…")
3. Misspelled or missing keywords or mistyping syntax within a block or expression
4. Attempting to use a reserved keyword as a variable name
5. Incorrectly indented code or other whitespace errors
6. Treating statements like expressions
7. Copying Python code into the REPL or copying from the REPL into a Python file

That’s a lot of options and they’re not the only options.
How should you approach fixing this problem?

Fixing SyntaxError: invalid syntax

The first step in fixing SyntaxErrors is narrowing down the problem.

I usually take the approach of:

1. Note the line number and error message from the traceback, keeping in mind that both of these just guesses that Python’s making
2. Working through the above list of common causes
3. Attempting to read the code as Python would, looking for syntax mistakes
4. Narrowing down the problem by removing blocks of code that I suspect may be the culprit

It’s easier to address that dreaded SyntaxError: invalid syntax exception when you’re familiar with its most common causes.
Let’s attempt to build up our intuitions around SyntaxError: invalid syntax by touring the common causes of this error message.

Upgrading Python improves error messages

Before diving into specific errors, note that upgrading your Python version can drastically improve the helpfulness of common error messages.

Take this error message:

$ python3 square.py
  File "/home/trey/square.py", line 2
    return [
    ^
SyntaxError: invalid syntax

On Python 3.10 it looks considerably different:

$ python3.10 square.py
  File "/home/trey/square.py", line 1
    def square_all(numbers:
                  ^
SyntaxError: '(' was never closed

We’re running the same square.py file in both cases:

def square_all(numbers:
    return [
        n**2
        for n in numbers
    ]

But Python 3.10 showed a much more helpful message: the line number, the position, and the error message itself are all much clearer for many unclosed parentheses and braces on Python 3.10 and above.

The dreaded missing colon is another example.
Any expression that starts a new block of code needs a : at the end.

Here’s the error that Python 3.9 shows for a missing colon:

$ python3 greet.py
  File "/home/trey/greet.py", line 10
    if name == "Trey"
                     ^
SyntaxError: invalid syntax

And here’s the same error in Python 3.10:

$ python3 greet.py
  File "/home/trey/greet.py", line 10
    if name == "Trey"
                     ^
SyntaxError: expected ':'

Much more helpful, right?
It’s still a SyntaxError exception, but the message is much clearer than simply invalid syntax.

Python 3.10 also includes friendlier error messages when you use = where you likely meant ==:

>>> name = "Trey"
>>> if name = "Trey":
  File "<stdin>", line 1
    if name = "Trey":
       ^^^^^^^^^^^^^
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?

Newer Python versions include more helpful error messages for missing commas, inline if expressions, unclosed braces/brackets/parentheses, and more.

If you have the ability to run your code on a newer version of Python, try it out.
It might help you troubleshoot your syntax errors more effectively.

Count your parentheses

Forgetting closing parentheses, brackets, and braces is also a common source of coding errors.

Fortunately, recent Python versions have started noting unclosed brackets in their SyntaxError messages.

When running this code:

def colors():
    c = ['red',
        'blue',
    return c

Python 3.9 used to show simply invalid syntax:

$ python3.9 colors.py
  File "/home/trey/colors.py", line 4
    return c
    ^
SyntaxError: invalid syntax

But Python 3.10 shows a more helpful error message:

$ python3.10 colors.py
  File "/home/trey/colors.py", line 2
    c = ['red',
        ^
SyntaxError: '[' was never closed

But sometimes Python can get a little confused when guessing the cause of an error.
Take this populate.py script:

import random
import names

random_list=["a1","a2","a3","b1","b2","b3","c1","c2","c3"]

with open("one.txt","w+") as one, 
     open("two.txt","w+") as two, 
     open("three.txt","w+") as three:
      for i in range(0,3):
          one.write("%sn" "%s" % (names.get_first_name(),
              random.choice(random_list))
          two.write("%sn" "%s" % (names.get_first_name(),
              random.choice(random_list))
          three.write("%sn" "%s" % (names.get_first_name(),
              random.choice(random_list))

When running this script, Python 3.10 shows this error message:

$ python3.10 populate.py
  File "/home/trey/populate.py", line 9
    one.write("%sn" "%s" %
              ^^^^^^^^^^^^^
SyntaxError: invalid syntax. Perhaps you forgot a comma?

The problem is that all 3 of those write method calls are missing closing parentheses.

Count your parentheses!

Many code editors highlight matching parentheses, brackets, and braces (when your cursor is at an opening parentheses the closing one will change color).
Use your code editor to see if each pair of parenthesis matches up properly (and that the one in matches seems correct).

Misspelled, missing, or misplaced keywords

Can you see what’s wrong with this line of code?

>>> drf sum_of_squares(numbers):
  File "<stdin>", line 1
    drf sum_of_squares(numbers):
        ^
SyntaxError: invalid syntax

We were trying to define a function, but we misspelled def as drf.
Python couldn’t figure out what we were trying to do, so it showed us that generic invalid syntax message.

What about this one?

>>> numbers = [2, 1, 3, 4, 7, 11, 18]
>>> squares = [n**2 for numbers]
  File "<stdin>", line 1
    squares = [n**2 for numbers]
                               ^
SyntaxError: invalid syntax

Python’s pointing to the end of our comprehension and saying there’s a syntax error.
But why?

Look a bit closer.
There’s something missing in our comprehension.

We meant type this:

>>> numbers = [2, 1, 3, 4, 7, 11, 18]
>>> squares = [n**2 for n in numbers]

We were missing the in in our comprehension’s looping component.

Misspelled keywords and missing keywords often result in that mysterious invalid syntax, but extra keywords can cause trouble as well.

You can’t use reserved words as variable names in Python:

>>> class = "druid"
  File "<stdin>", line 1
    class = "druid"
          ^
SyntaxError: invalid syntax

Python sees that word class and it assumes we’re defining a class.
But then it sees an = sign and gets confused and can’t tell what we’re trying to do, so it throws its hands in the error and yells invalid syntax!

This one is a bit more mysterious:

>>> import urlopen from urllib.request
  File "<stdin>", line 1
    import urlopen from urllib.request
                   ^^^^
SyntaxError: invalid syntax

That looks right, doesn’t it?
So what’s the problem?

In Python the import…from syntax is actually a from…import syntax.
We meant to write this instead:

>>> from urllib.request import urlopen

Watch out for misspelled keywords, missing keywords, and re-arranged syntax.
Also be sure not to use reserved words as variable names (e.g. class, return, and import are invalid variable names).

Subtle spacing problems

Can you see what’s wrong in this code?

>>> class Thing:
...     def __init _(self, name, color):
  File "<stdin>", line 2
    def __init _(self, name, color):
               ^
SyntaxError: invalid syntax

Notice the extra space in the function name (__init_ _ instead of __init__)?

Can you identify what’s wrong in this line?

>>> class Thing:
...     def__init__(self, name, color):
  File "<stdin>", line 2
    def__init__(self, name, color):
                                  ^
SyntaxError: invalid syntax

This one might be harder to spot.

Everything on that line is correct except that there’s no space between def and __init__.

When one space character is valid, you can usually use more than one space character as well.
But adding an extra space in the middle of an identifier or removing spaces where there should be spaces can often cause syntax errors.

Forgotten quotes and extra quotes

If you code infrequently, you likely forget to put quotes around your strings often.
This is a very common mistake, so rest assured that you’re not alone!

Forgotten quotes can sometimes result in this cryptic invalid syntax error message:

>>> print(Four!) if n
  File "<stdin>", line 1
    print(Four!) if n
              ^
SyntaxError: invalid syntax

Be careful with quotes within quotes:

>>> question = 'What's that?'
  File "<stdin>", line 1
    question = 'What's that?'
                     ^
SyntaxError: invalid syntax

You’ll need to switch to a different quote style (using double quotes for example) or escape those quotes.

Mixing up your symbols

Sometimes your syntax might look correct but you’ve actually confused one bit of syntax for another common bit of syntax.

That’s what happened here:

>>> things = {duck='purple', monkey='green'}
  File "<stdin>", line 1
    things = {duck='purple', monkey='green'}
              ^^^^^^^^^^^^^
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?

We’re trying to make a dictionary and we’ve accidentally used = instead of : to separate our key-value pairs.

Here’s another dictionary symbol mix up:

>>> states = [
...     'Oregon': 'OR',
  File "<stdin>", line 2
    'Oregon': 'OR',
            ^
SyntaxError: invalid syntax

It looks like we’re trying to define a dictionary, but we started with an open square bracket ([) instead of an open curly brace ({).

Another common syntax mistake is missing periods:

  File "/home/trey/file_info.py", line 15
    size = path.stat()st_size
                      ^^^^^^^
SyntaxError: invalid syntax

We’re trying to access the st_size attribute on the object returned from that path.stat() call, but we’ve forgot to put a . before st_size.

Sometimes syntax errors are due to characters being swapped around:

>>> name = "Trey"
>>> name[]0
  File "<stdin>", line 1
    name[]0
         ^
SyntaxError: invalid syntax

And some syntax errors are due to extra symbols you didn’t intend to write:

>>> name = "Trey"
>>> name.lower.()
  File "<stdin>", line 1
    name.lower.()
               ^
SyntaxError: invalid syntax

We wrote an extra . before our parentheses above.

Indentation errors in disguise

Sometimes a SyntaxError is actually an indentation error in disguise.

For example this code has an else clause that’s too far indented:

import sys

name = sys.argv[1]

if name == "Trey":
    print("I know you")
    print("Your name is Troy... no, Trent? Trevor??")
    else:
        print("Hello stranger")

When we run the code we’ll see a SyntaxError:

$ python greet.py
  File "/home/trey/greet.py", line 8
    else:
    ^^^^
SyntaxError: invalid syntax

Indentation issues often result in IndentationError exceptions, but sometimes they’ll manifest as SyntaxError exceptions instead.

Embedding statements within statements

A «statement» is either a block of Python code or a single line of Python code that can stand on its own.

An «expression» is a chunk of Python code that evaluates to a value.
Expressions contain identifiers (i.e. variables), literals (e.g. [1, 2], "hi", and 4), and operators (e.g. +, in, and *).

In Python we can embed one expression within another.
But some expressions are actually «statements» which must be a line all on their own.

Here we’ve tried to embed one statement within another:

>>> def square_all(numbers):
...     return result = [n**2 for n in numbers]
  File "<stdin>", line 2
    return result = [n**2 for n in numbers]
                  ^
SyntaxError: invalid syntax

Assignments are statements in Python (result = ... is a statement).
Python’s return is also a statement.
We’ve tried to embed one statement inside another and Python didn’t understand us.

We likely meant either this:

def square_all(numbers):
    result = [n**2 for n in numbers]
    return result

Or this:

def square_all(numbers):
    return [n**2 for n in numbers]

Here’s the same issue with the global statement (see assigning to global variables):

>>> def connect(*args, **kwargs):
...     global _connection = sqlite3.connect(*args, **kwargs)
  File "<stdin>", line 2
    global _connection = sqlite3.connect(*args, **kwargs)
                       ^
SyntaxError: invalid syntax

And the same issue with the del statement:

trey_count = del counts['Trey']
  File "<stdin>", line 1
    trey_count = del counts['Trey']
                 ^^^
SyntaxError: invalid syntax

If assignment is involves in your statement-inside-a-statement, an assignment expression (via Python’s walrus operator) may be helpful in resolving your issue.
Though often the simplest solution is to split your code into multiple statements over multiple lines.

Errors that appear only in the Python REPL

Some errors are a bit less helpful within the Python REPL.

Take this invalid syntax error:

def square_all(numbers:
    return [
  File "<stdin>", line 2
    return [
    ^^^^^^
SyntaxError: invalid syntax

We’ll see that error within the Python REPL even on Python 3.11.

The issue is that the first line doesn’t have a closing parentheses.
Python 3.10+ would properly point this out if we ran our code from a .py file instead:

$ python3.10 square.py
  File "/home/trey/square.py", line 1
    def square_all(numbers:
                  ^
SyntaxError: '(' was never closed

But at the REPL Python doesn’t parse our code the same way (it parses block-by-block in the REPL) and sometimes error messages are a bit less helpful within the REPL as a result.

Here’s another REPL-specific error:

>>> def greet(name):
...     print(f"Howdy {name}!")
... greet("Trey")
  File "<stdin>", line 3
    greet("Trey")
    ^^^^^
SyntaxError: invalid syntax

This is valid Python code:

def greet(name):
    print(f"Howdy {name}!")
greet("Trey")

But that can’t be copy-pasted directly into the REPL.
In the Python REPL a blank line is needed after a block of code to end that block.

So we’d need to put a newline between the function definition and the function call:

>>> def greet(name):
...     print(f"Howdy {name}!")
...
>>> greet("Trey")
Howdy Trey!

Some errors are due to code that feels like it should work in a Python REPL but doesn’t.
For example running python from within your Python REPL doesn’t work:

>>> python greet.py
  File "<stdin>", line 1
    python greet.py
           ^^^^^
SyntaxError: invalid syntax
>>> python -m pip install django
  File "<stdin>", line 1
    python -m pip install django
              ^^^
SyntaxError: invalid syntax

The above commands would work from our system command-prompt, but they don’t work within the Python REPL.

If you’re trying to launch Python or send a command to your prompt outside Python (like ls or dir), you’ll need to do it from your system command prompt (Terminal, Powershell, Command Prompt, etc.).
You can only type valid Python code from within the Python REPL.

Problems copy-pasting from the REPL

Copy-pasting from the Python REPL into a .py file will also result in syntax errors.

Here’s we’re running a file that has >>> prefixes before each line:

$ python numbers.py
  File "/home/trey/numbers.py", line 1
    >>> n = 4
    ^^
SyntaxError: invalid syntax

This isn’t a valid Python program:

>>> n = 4
>>> print(n**2)

But this is a valid Python program:

You’ll need to be careful about empty lines when copy-pasting from a .py file into a Python REPL and you’ll need to be careful about >>> and ... prefixes and command output when copy-pasting from a REPL into a .py file.

The line number is just a «best guess»

It used to be that the line number for an error would usually represent the place that Python got confused about your syntax.
That line number was often one or more lines after the actual error.

In recent versions of Python, the core developers have updated these line numbers in an attempt to make them more accurate.

For example here’s an error on Python 3.9 due to a missing comma:

$ python3.9 greet.py
  File "/home/trey/greet.py", line 4
    name
    ^
SyntaxError: invalid syntax

And here’s the same error in Python 3.10:

$ python3.10 greet.py
  File "/home/greet.py", line 3
    "Hello there"
    ^^^^^^^^^^^^^
SyntaxError: invalid syntax. Perhaps you forgot a comma?

Python’s given us a helpful hint on Python 3.10.
But it’s also made a different guess about what line the error is on.

As you can see from the greet.py file, line 3 ("Hello there") is the better guess in this case, as that’s where the comma is needed.

def greet(name):
    print(
        "Hello there"
        name
    )

While deciphering tracebacks, keep in mind that the line number is just Python’s best guess as to where the error occurred.

SyntaxError exceptions happen all the time

If your code frequently results in SyntaxError exceptions, don’t fret.
These kinds of exceptions happen all the time.
When you’re newer to Python, you’ll find that it’s often a challenge to remember the exact syntax for the statements you’re writing.

But more experienced Python programmers also experience syntax errors.
I make typos in my code quite often.
I have a linter installed in my text editor to help me catch those typos though.
I recommend searching for a «Python» or «Python linter» extension for your favorite code editor so you can spot these issues quickly every time you save your .py files.

Once you get past syntax errors, you’ll likely hit other types of exceptions. Watch the exception screencast series for more on reading tracebacks and exception handling in Python.