Python raises “SyntaxError: unterminated triple-quoted string literal” when you use a pair of triple quotes ("""
or '''
) around a multi-line string literal, but the ending part is missing.
Here’s what the error looks like on Python version 3.11:
File /dwd/sandbox/test.py, line 1
message = '''Readme:
^
SyntaxError: unterminated triple-quoted string literal (detected at line 3)
This post was originally published on decodingweb.dev as part of the Python Syntax Errors series.
On the other hand, the error "SyntaxError: unterminated triple-quoted string literal" means Python was expecting a closing triple-quote, but it didn't encounter any:
# 🚫 SyntaxError: unterminated triple-quoted string literal (detected at line 5)
message = """Python is a high-level,
general-purpose
programming language
Adding the missing quotation mark fixes the problem instantly:
# ✅ Correct
message = """Python is a high-level,
general-purpose
programming language"""
How to fix "SyntaxError: unterminated triple-quoted string literal"
The error "SyntaxError: unterminated triple-quoted string literal" occurs under various scenarios:
- Missing the closing triple quotes
- When a string value ends with a backslash (
\
) - Opening and closing triple quotes mismatch
1. Missing the closing triple quotes: As mentioned earlier, the most common reason behind this error is to forget to close your "triple-quoted string literal" with triple quotes ("""
) - perhaps you put a double-quote (""
) instead of three:
# 🚫 SyntaxError: unterminated triple-quoted string literal (detected at line 5)
message = """Python is a high-level,
general-purpose
programming language""
Needless to say, adding the missing quotation mark fixes the problem:
# ✅ Correct
message = """Python is a high-level,
general-purpose
programming language"""
2. When a string value ends with a backslash (): Based on Python semantics, triple quotes work as a boundary for multi-line string literals.
However, if your string literal ends with a backslash, the backslash (as the escaping character) will neutralize one of the three quotation marks - making our magical triple-quote lose its quoting behavior.
In programming terminology, we call it an escape character.
Imagine you need to define a string that ends with a \
, like a file path on Windows because Windows uses a backslash as the path separator.
But this path separator happens to be the escaping character in most programming languages, including Python:
# 🚫 SyntaxError: unterminated triple-quoted string literal (detected at line 3)
message = '''Readme:
The file is located under the following path:
c:\files\'''
In the above code, the last \
escapes the first (of the three) quotation marks, leaving our string unterminated. As a result, Python raises "SyntaxError: unterminated triple-quoted string literal".
To fix it, we use a double backslash \\
instead of one. The first \
escapes the escaping behavior of its following backslash, and as a result, the \
would be another ordinary character in the string.
# ✅ Escaping a slash in a triple-quoted string literal
message = '''Readme:
The file is located under the following path:
c:\files\\'''
3. Opening and closing triple quotes mismatch: The opening and closing triple-quotes must be identical, meaning if the opening part is '''
, the closing part must be '''
too.
The following code raises the error since we open it with '''
but close it with """
.
# 🚫 SyntaxError: unterminated triple-quoted string literal (detected at line 3)
message = '''Readme:
The file is located under the following path:
c:\files\"""
No matter which one you choose, they need to be identical:
# ✅ Opening and closing quotation marks match
message = '''Python is a high-level,
general-purpose
programming language'''
Alright, I think it does it. I hope this quick guide helped you solve your problem.
Thanks for reading.
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