Syntax Error: invalid syntax

Syntax Error: invalid syntax

The Python "SyntaxError: invalid syntax" occurs when there is invalid syntax in the code. This means the code is not "proper" Python and is missing something, has extra characters, or is an invalid usage of a statement (such as if-else, for loops, try-except). This can be fixed by debugging the code to figure out where the error is.

What causes SyntaxError

• Misspelled reserved keywords
• Missing required spaces
• Missing parentheses, brackets, and quotes
• Missing operators
• Mistaking dictionary syntax
• Using the wrong indentation
• Invalid usage of blocks (such as if-else, for loops, try-except)
• Invalid variable declarations
• Invalid function definitions or calls

Here are some examples that cause a SyntaxError.

# ⛔️ SyntaxError: invalid syntax
# missing quotes around `Hello`
print(Hello)

# ✅ this runs
print("Hello")

# -----------------------

# ⛔️ SyntaxError: invalid syntax
# for loop statement requires code inside the loop
for item in box:

# ✅ this runs
for item in box:
  print(item)

# -----------------------

# ⛔️ SyntaxError: invalid syntax
# there is a missing comma
# each element of a dictionary needs to be separated by a comma
trees = {
  "maple": 5,
  "oak": 14
  "redwood": 9
}

# ✅ this runs
trees = {
  "maple": 5,
  "oak": 14,
  "linden": 9
}

Tips for debugging

When a SyntaxError is reported on a line that appears correct, try commenting out that line. If the error moves to the next line, then:

1. Both lines have a problem, or
2. The previous line has a problem which is being carried forward

The second one is more likely, especially if commenting out another line causes the error to move again.

Here is an example.

# this is missing a closing integer and parentheses
number_of_squares = (5 +

# ⛔️ SyntaxError: invalid syntax will occur on this line
number_of_circles = 8

# -----------------------
# ✅ this runs
number_of_squares = (5 + 8)
number_of_circles = 8

The error is produced on the second line, even though the problem is caused by the first line.

Conclusion

The Python "SyntaxError: invalid syntax" occurs when there is invalid syntax in the code. This means the code is not "proper" Python and is missing something, has extra characters, or is an invalid usage of a statement (such as if-else, for loops, try/except). This can be fixed by debugging the code to figure out where the error is.