Invalid Syntax Errors in Python: Meaning, Examples, and Fixes

However, in your learning journey, you may often encounter the “invalid syntax error in Python” issue, which can sometimes be frustrating. In today’s guide, we will help you learn how to fix syntax error in Python using several simple and accessible solutions. So, without wasting any more of your time, let’s dive right in!

Key Takeaways

• Syntax errors happen when Python cannot understand your code, usually because of small issues like missing punctuation, wrong indentation, or incorrect use of keywords.
• Reading the syntax error message is the fastest way to find the problem, since Python tells you the exact line where it found the issue.
• Most syntax errors come from simple typos, so always double-check brackets, quotes, colons, and assignment symbols.
• Modern coding tools like VS Code make debugging Python code easier since they highlight errors in realtime as you write the code.
• Good Python coding practices like using 4 spaces for indentation, running code very often, and keeping everything clean and readable help prevent many syntax errors,

What Is a Syntax Error in Python?

An invalid syntax error in Python occurs when the code you write breaks the rules of the language. The Python program expects your code to follow a predetermined structure, and if you wrote something incorrectly, it won’t understand the instructions triggering a syntax error. Python has this syntax error messaging function to enable users to know what is going on. 

Some of the common errors most new Python programmers make include; a missing colon, unmatched brackets, or a wrong indentation. These may seem like minor issues, but they break Python rules, so your program won’t run until you fix them. Most modern IDEs (integrating development environments) do highlight the lines of code where one of these syntax errors might be. 

Understanding syntax errors and how to fix them is important because it helps you write cleaner and accurate code. Also remember that most of the coding time is spent in debugging, which also includes fixing any syntax errors in your Python code. So, you shouldn’t look at it as wasting time.

How Python Reports Syntax Errors

Like most programming languages, Python is designed to stop running a program if it has any invalid syntax errors. When you try running such Python code, an invalid error message will pop up in the command line, giving all the crucial information such as the type of error and where it happened. 

As stated earlier, most modern IDEs will highlight the invalid code within your Python program, which makes it easier to spot and fix. Before these modern IDEs, developers had to look through every line of code to spot errors, which consumed a lot of time. 

Common Causes of Syntax Errors

Whether you are writing simple Python scripts or complex programs, there are so many syntax errors that may show up when you finally try to run the program. Most of these syntax errors in Python come from simple typos or small formatting mistakes. It is common for even experienced developers to run into them from time to time, so it is not just a problem faced by beginners. 

In this section, we will walk you through some of the most common invalid syntax errors that you may encounter when writing Python code. 

Missing or Mismatched Parentheses, Brackets, and Quotes

This is by far one of the most common ones. Forgetting to close parentheses, brackets, or quotes will automatically break your program and stop it from compiling or running.

Syntax Error Examples:

Here are some coding examples of how this syntax error might happen. 

Missing parenthesis:

print("Hello"

In the above line of code, you can easily see that the developer forgot to add the last bracket. The correct syntax for this is:

print ("Hello")

Mismatched brackets:

my_list = [1, 2, 3)

In Python, you are supposed to use the same type of brackets in any given statement. So, if you use “(“ to open the statement, you should then use “)” to close and not “]”. So, in this case, the current syntax is:

 my_list = (1, 2, 3)

Unclosed quotes

name = "Tom

Quotes may seem like something small, but they matter a lot as far as Python syntax is concerned. In this case, the correct syntax is:

 name = "Tom"

Misplaced or Missing Punctuation (Commas, Colons, Periods)

Many developers have encountered this invalid syntax error, so it is also up there among the most popular ones. When coding in Python most structures will always require specific punctuation. So, missing a colon or placing a comma incorrectly will instantly lead to a invalid syntax error when you try to run your Python code. 

Examples:

Missing colon after a function or loop:

def greet()
    print("Hello")

In this case the developer was trying to define a function, but they forgot to add a colon. The correct syntax for this Python code snippet is: 

def greet():
    print("Hello")

Misplaced comma in a list:

numbers = [1 2, 3]

Here the developer was trying to define a list, but they didn’t include a common to separate the first two digits. The correct syntax in this case is: 

numbers = [1, 2, 3]

Misspelled or Misused Python Keywords

Python has several keywords that are reserved for executing certain tasks. Every program written in Python must correctly use these keywords. So, incorrectly spelling or misusing them will instantly break your Python code if you try to run it. 

Examples:

Spelling print incorrectly:

prnt("Hello")

For this code snippet, the developer was trying to write a simple program for printing the word “Hello”, but they misspelt an important keyword: print. The correct syntax is:

print("Hello")

Using a reserved keyword as a variable name:

if = 5

It is important to note that reserved keywords are not supposed to be used as variable names in your Python code. For instance, you can not use the word “if” as variable or function names since it is a reserved keyword in Python. 

Illegal Characters or Invalid Variable Names

In Python, all your variable names must follow certain rules. Some of these rules include: 

• They must start with a letter or underscore.
• They cannot contain spaces or special symbols.
• They cannot start with a number.

Here are some examples of wrong variant names and their correct versions

Wrong:

2name = "Tom"

first-name = "Tom"

my variable = 10

Correct:

name2 = "Tom"

first_name = "Tom"

my_variable = 10

Errors explained

• The syntax error in the first one was using a number at the beginning of the variable name
• In the second statement, a special symbol was used in the variable name
• The last variable declaration had a space within the variable name (my variable)

Invalid Indentation

Indentation is one of the ways languages like Python structure code to make it more readable. In Python, indentation is used to define blocks of code. Inconsistent indentation or mixing tabs and spaces will often trigger syntax errors when you run your Python code. 

Example:

if x > 5:
print("Greater")   # Not indented

In this example, the developer did not add proper indentation after the if statement. The correct syntax for this Python code snippet is supposed to be as follows: 

if x > 5:
print("Greater") #Indented using a single tab. 

Mixed tabs and spaces issue:

if x > 5:
    print("Hi")
print("Hello")   # Tab and spaces mixed

In this Python code, the developer used four spaces in line 2 and a single tab in line 3, which goes against the rules of Indentation in Python. The correct syntax for this Python code snipped is as follows: 

if x > 5:
    print("Hi")
    print("Hello")   # In this case four spaces were used for both lines. 

Invalid Use of the Assignment Operator (=)

The assignment operator is one of the most important operators in Python and you will often use it. In Python: 

• = is used for assignment
• == is used for comparison.

Using = in a conditional statement will always lead to a syntax error causing your program not to run. 

Here is an example:

if x = 5:   # Wrong
    print("Hello")

In this case, the developer used “=” instead of “==“ which goes against the rules of using this operator. Below is the correct version of the Python code. 

Correct version:

if x == 5:
    print("Hello")

Defining or Calling Functions Improperly

When writing Python code, you will often have to write functions. One of the common mistakes most developers make is forgetting the colon after def or leaving out parentheses when calling a function.

Here are some common examples: 

Missing colon:

def greet()
    print("Hello")

In this example, a colon was not added at the end of the function definition. The correct syntax for this Python code snippet is as follows: 

def greet():
    print("Hello")

Forgetting parentheses when calling a function:

When calling the above function, you are supposed to include parentheses. So, it should be: “greet()” instead of “greet”. Ignoring the parentheses will lead to a syntax error. 

Version-Dependent Syntax Differences

Some syntax works only in certain Python versions. For example:

• Python 2 uses print “Hello”
• Python 3 requires print(“Hello”)

Other features like f-strings only work in Python 3.6+, so using them in older versions will cause a syntax error. When coding in Python, it is important to remember the coding rules of the specific Python version you are using. So, if you encounter a syntax error that seems to be unusual, it could be because of the Python version you are using.

How to Fix Syntax Errors in Python

Syntax errors can be frustrating to fix, especially if you are a new developer or used to a different programming language. Fortunately, with modern tools, it has become a lot easier to fix syntax errors. In this section, we will explore some of the easiest ways to resolve the common syntax errors.

• Read the invalid error message carefully: Like most languages, Python will clearly tell you the line number and type of syntax error. For instance, if there is an error in syntax highlighting the use of a keyword in a variable name, Python will tell you. So, first check the line number that Python highlights. Also remember to check the nearby lines too.
• Look for missing punctuation: Python’s syntax rules require that you use punctuation symbols like colons, brackets, and quotes correctly. If you get a syntax error, check for missing commas, colons, parentheses, brackets, or quotes. Check your lists, functions, conditional statements, and all the other sections of your Python code and ensure that punctuation symbols are not missing or used incorrectly. 
• Fix indentation issues: Indentation also causes syntax errors and it can be confusing to maintain consistency, especially if you are new to this programming language or software development in general. Python uses indentation to improve code readability. To fix indentation issues, double your Python code and make sure indentation is properly made under if, for, while, functions, etc. When using Python, always avoid mixing spaces and tabs—use one of the two consistently throughout your Python code. 
• Test after each small fix: As you get used to programming, you will notice that it is common to have more than one syntax error. Attempting to fix them all at once may actually waste more time. So, we recommend you fix one line at a time. Run the code again after each fix to confirm the change worked. You should notice the size of the invalid error messages shrinking after each fix. 
• Use a code editor that highlights errors: Most of the modern IDEs such as VS Code or PyCharm show red underlines for mistakes, helping you debug faster. As you write your Python code, these tools will highlight the invalid code in realtime. Always ensure to fix this invalid code immediately to avoid wasting later on. 
• Compare Your code with working Python code: Sometimes a small syntax error can stop your Python code from running, and it can be hard to notice it right away. If you ever run into this kind of situation, check an example or look back at code that already works correctly. Comparing your current code with these correct versions makes it easy to spot these hard-to-find invalid code. 
• Use AI tools: Using LLMs tools like ChatGPT and Claude has become one of the common ways developers debug their Python code. Simply copy the invalid error message into the Claude and ChatGPT chatbot and it will help you identify the error. Please note that these tools may not be perfect, but 90 to 95% of the time, they will spot the common errors. They can even help you rewrite the entire Python code snippet with the correct version.

Preventing Syntax Errors Before They Happen

• Use 4 spaces for indentation: Even though Python allows any consistent indentation, the standard rule is 4 spaces. Also remember using the same number of spaces (4 to be exact) throughout your script. If possible it is also best to avoid using tabs. Your Python code will be much more readable and easier to debug (by you and others) if you use 4 spaces instead of tabs. Most IDEs also automatically use 4 spaces indentation by default instead of tabs.  
• Run your code often: Avoid writing big chunks of code before you can compile and run them. Always run the code very often to catch problems early before they become harder to find later. For instance when using functions, you can always run the code after every function and fix any errors that may come up before proceeding. 
• Write clean and readable code: Readability is one of the metrics that differentiate good and bad code. To improve readability, always add spaces around operators, break long lines, and keep code organized. You should also include comments in your code to explain some of your choices—this helps, especially when collaborating with others to work on a specific project. 
• Use a linter or formatting tool: There are several linter tools that you can use to spot any error in your Python code in real time. Some of the most popular ones include Pylint, Black, Pyright, Flake8, and Mypy. Fortunately most of these can be integrated in modern IDEs. For instance, the Python extension for VS Code includes Pylint, Flake8, and Mypy. 
• Pay attention to punctuation: The Python interpreter will trigger invalid syntax errors if your Python code doesn’t comply with the punctuation rules of the language. So, as you write your Python code, take time to check  every colon after if, elif, else, for, while, try, and except. Make sure the appropriate punctuation is included whenever necessary. Also make sure that all brackets and quotes are properly opened and closed. 
• Practice consistently: Like with any other technical skill, you can only get better at avoiding simple errors or spotting them when they occur the more you practice. The more you code, the easier it becomes to avoid syntax mistakes. So, make it a habit to code everyday if possible. After a couple of months, you may notice that some of the errors occurred because you still need Python or programming in general.  

Final Thoughts

This guide has covered everything you need to know about Python syntax errors. We have covered the common errors like missing and improper punctuation, inconsistent indentation, misuse of keywords, and more. Knowing these common typing errors and how to fix them makes it a lot easier to learn and start building things with Python. 

It is also important to remember the Python best practices like using 4 spaces for indentation, running your code often, and making your programs/scripts readable can help minimize the chances of making errors. 

Also, remember to use tools like linters or AI solutions like Claude as these can help speed up the process of spotting invalid code errors. We hope you understood these common invalid code errors, what causes them and the fixes you can use to resolve them. 

FAQs

What is the difference between syntax errors and runtime errors in Python?

These are two of the most common types of Python errors. Syntax errors usually happen when the Python interpreter encounters a character or phrase it doesn’t understand. Such invalid code errors include missing a colon or bracket. On the other hand, runtime errors happen while the program is running, even if the code is written correctly. An example of this would be dividing a number by zero.

How do I find where the syntax error is in my Python code?

When an error occurs, look at the invalid error message in your terminal. It usually shows a line number and a small arrow (^) pointing to the problem. Go and check that line and the one above, since sometimes the mistake is before the line Python shows.

Why does Python say “SyntaxError: invalid syntax” even when my code looks fine?

This could be due to small issues that may be hard to spot. Such issues include a missing colon after if, for, or while, a missing quote or bracket, wrong indentation, using a keyword (like if or for) as a variable name. So, take time to check these small, yet common issues and fix them to solve the problem. 

What tools help detect syntax errors automatically?

Modern code editors like VS Code, PyCharm, and Thonny highlight mistakes in realtime as you type the code. Linters such as Pylint or Flake8 can scan your Python code for errors before running it. The good news is that these can all be integrated into your IDE, making the debugging experience more seamless.