Error
Error Code:
22025
PostgreSQL Error 22025: Invalid Escape Sequence
Description
This `Data Exception` error occurs in PostgreSQL when a string literal contains a backslash character (`\`) followed by a character sequence that is not recognized as a valid escape sequence. It often indicates a syntax issue in SQL queries or data being inserted, particularly when dealing with special characters.
Error Message
invalid escape sequence
Known Causes
4 known causesUnrecognized Escape Character
A backslash in a string literal is followed by a character not defined as a valid escape sequence (e.g., `\x` where `x` is not a recognized escape character).
Incorrect E Prefix Usage
Attempting to use C-style backslash escapes without the `E` prefix on the string literal, or using `E` incorrectly with non-escape characters.
Literal Backslash Not Escaped
A literal backslash character is intended but not properly escaped as `\\`, especially when `standard_conforming_strings` is enabled.
External Data with Malformed Escapes
Imported data or user input contains escape sequences that conflict with PostgreSQL's string literal parsing rules.
Solutions
3 solutions available1. Escape Special Characters in String Literals easy
Properly escape backslashes and other special characters within string literals.
1
Identify the string literal that contains the invalid escape sequence. This is typically a string being inserted or updated into a table, or a string used in a query.
2
In SQL string literals, a backslash (`\`) is used to escape the next character. If you intend to have a literal backslash, you must escape it by doubling it (`\\`). Similarly, other special characters like single quotes (`'`) within string literals must be escaped by doubling them (`''`).
UPDATE my_table SET my_column = 'This is a string with a literal backslash: \\';
INSERT INTO another_table (message) VALUES ('This string contains a single quote: ''quote''');3
If the string originates from an application, ensure the application code correctly escapes special characters before passing them to PostgreSQL. This might involve using parameterized queries or specific string escaping functions provided by your programming language's PostgreSQL driver.
2. Use Dollar-Quoted Strings for Complex Literals easy
Employ dollar-quoted strings to avoid the need for escaping special characters.
1
When dealing with strings that contain many backslashes or single quotes, standard SQL string literals (`'...'`) can become cumbersome and error-prone due to the need for extensive escaping.
2
Use dollar-quoted strings, which are delimited by `$$` or a user-defined tag enclosed in dollar signs (e.g., `$TAG$...$TAG$`). Within a dollar-quoted string, no characters are interpreted as escape sequences, including backslashes and single quotes.
UPDATE my_table SET my_column = $$This string contains a literal backslash \ and a single quote ' without any escaping.$$;
INSERT INTO another_table (message) VALUES ($MY_MESSAGE$This is a complex string with \\ backslashes and '' quotes.$MY_MESSAGE$);3
Choose a tag that does not appear within the string itself to avoid premature termination of the dollar-quoted string. If your string contains `$$`, use a tagged dollar-quoted string.
3. Review Application Code for String Handling medium
Inspect your application's code that interacts with PostgreSQL for incorrect string escaping.
1
Pinpoint the specific query or operation in your application that is causing the 'invalid escape sequence' error. This often involves looking at application logs or debugging your code.
2
Examine how strings are constructed and passed to PostgreSQL. If you are manually concatenating SQL queries with strings, ensure that any special characters within those strings are properly escaped according to PostgreSQL's rules (as described in Solution 1).
3
The most robust solution is to use parameterized queries (prepared statements). Most PostgreSQL drivers and ORMs provide mechanisms for this. This separates the SQL command from the data, preventing SQL injection and automatically handling escaping of special characters.
Example in Python with psycopg2:
python
cursor.execute("INSERT INTO my_table (my_column) VALUES (%s)", ('This string has a \ character.',))
4
If you cannot use parameterized queries, use the escaping functions provided by your PostgreSQL driver or library. For example, in many languages, there's a way to get a 'safe' or 'escaped' version of a string for SQL.