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Description

MySQL Error 3141, 'Invalid JSON text', indicates that a string provided to a MySQL JSON function or a JSON column could not be parsed as valid JSON. This typically occurs when the input string has syntax errors, is malformed, or contains invalid characters, preventing MySQL from processing it correctly.

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Error Message

Invalid JSON text in argument %u to function %s: %s at position %u.%s

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Known Causes

4 known causes

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Malformed JSON Syntax

The provided string does not adhere to valid JSON syntax rules, such as missing quotes, commas, brackets, or incorrect nesting of objects or arrays.

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Incorrect Data Type or Value

A non-string value, or a string that is not intended to be JSON, was passed to a MySQL function or column expecting properly formatted JSON text.

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Character Encoding Issues

Improper character encoding (e.g., non-UTF-8 characters) can corrupt JSON strings, leading to parsing errors by the MySQL server.

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Truncated JSON String

The JSON text was incomplete due to truncation, often caused by column size limits, network issues, or client-side data handling problems.

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Solutions

3 solutions available

1. Validate and Correct JSON Data Before Insertion/Update easy

Ensure the JSON string being passed to a MySQL JSON function is syntactically correct.

1

Identify the specific SQL statement (INSERT or UPDATE) that is causing the error and the column it's operating on.

2

Examine the JSON data being inserted or updated. Look for common JSON syntax errors such as:

1. Missing or extra commas.
2. Unquoted string values (keys and values must be enclosed in double quotes).
3. Incorrectly escaped special characters within strings (e.g., a literal backslash '\' needs to be '\\').
4. Mismatched braces `{}` or brackets `[]`.
5. Invalid data types (e.g., using single quotes for strings).

3

Use a JSON validator tool (online or a library in your application code) to check the validity of the JSON string before sending it to MySQL.

4

Correct the JSON string in your application code or SQL query to adhere to valid JSON syntax.

Example of incorrect JSON:
{'name': 'John Doe', 'age': 30}

Example of correct JSON:
{"name": "John Doe", "age": 30}

2. Inspect MySQL Error Logs for Precise Location medium

Use MySQL error logs to pinpoint the exact invalid JSON text and its position.

1

Locate your MySQL error log file. The location varies by operating system and installation method. Common locations include `/var/log/mysql/error.log` (Linux) or within the MySQL data directory.

2

Open the error log file with a text editor or use command-line tools.

tail -f /var/log/mysql/error.log  # For real-time monitoring
grep '3141' /var/log/mysql/error.log # To find all occurrences

3

Search for the error message 'MySQL Error 3141: Invalid JSON Text in Function'. The log entry will often include the specific invalid text and the position where the parser encountered the issue.

Example log entry:
2023-10-27T10:30:00.123456Z 1 [ERROR] Invalid JSON text in argument 1 to function json_extract: ... at position 15.unexpected token.

4

Use the provided position and invalid text to debug the JSON string in your application or SQL query.

3. Use MySQL's JSON_VALID Function for Pre-Checks medium

Proactively check JSON validity within SQL before attempting JSON operations.

1

Before calling any MySQL JSON functions (like `JSON_EXTRACT`, `JSON_SET`, `JSON_OBJECT`, etc.), use the `JSON_VALID()` function to verify the JSON string.

SELECT JSON_VALID('{"name": "John Doe", "age": 30}'); -- Returns 1 (true)
SELECT JSON_VALID('{"name": John Doe}'); -- Returns 0 (false)

2

In your application code, retrieve the potential JSON data and check its validity using `JSON_VALID()` in a `SELECT` statement. If `JSON_VALID()` returns 0, handle the invalid data appropriately (e.g., log the error, skip the record, or attempt to clean it).

DECLARE json_data TEXT;
-- ... retrieve json_data ...
IF JSON_VALID(json_data) THEN
    -- Proceed with JSON operations
    INSERT INTO my_table (json_column) VALUES (json_data);
ELSE
    -- Handle invalid JSON, e.g., log an error
    INSERT INTO error_log (message) VALUES (CONCAT('Invalid JSON encountered: ', json_data));
END IF;

3

Alternatively, you can perform this check within your application's programming language using its JSON parsing capabilities before sending the data to MySQL.

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Related Errors

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