ER_INVALID_CAST_TO_JSON occurs when MySQL cannot convert a value to valid JSON using CAST or CONVERT.
ER_INVALID_CAST_TO_JSON means MySQL failed to convert a value to JSON. Ensure the source string is valid JSON or use JSON_OBJECT/JSON_ARRAY functions before casting to fix the error.
ER_INVALID_CAST_TO_JSON
MySQL raises ER_INVALID_CAST_TO_JSON (error 3147, SQLSTATE 22032) when a CAST(value AS JSON) or CONVERT(value, JSON) operation encounters data that is not valid JSON.
The server rejects the conversion to protect data integrity, so the statement fails immediately.
Improperly formatted strings are the primary trigger. Any missing quotes, unmatched braces, or illegal escape sequences make the string invalid JSON.
Attempting to cast binary, numeric, or NULL values directly to JSON without stringifying them also triggers the error.
Using character sets that change byte sequences (e.g., casting from latin1) can corrupt JSON syntax and cause MySQL to reject the cast.
Validate and clean your data before casting. Use JSON_VALID to test strings and JSON_OBJECT or JSON_ARRAY to build compliant JSON instead of manual concatenation.
Always specify the correct character set in your literals so MySQL interprets bytes correctly.
Bulk imports often fail when a text column contains stray control characters. Preprocess files to remove them, or wrap the load in a SET @tmp = IF(JSON_VALID(col), col, NULL) pattern.
Stored procedures sometimes build JSON via CONCAT. Switch to JSON_OBJECT for structural safety and future-proofing.
Store JSON in dedicated JSON columns to let MySQL validate inserts automatically. Never build JSON by hand in application code without using a proper encoder.
Add CHECK (JSON_VALID(col)) constraints in MySQL 8.0.16+ to catch invalid data early.
ER_INVALID_JSON_TEXT (3140) signals bad JSON during insert or update rather than cast. Fix it by sanitizing the incoming value.
ER_INVALID_JSON_CHARSET (3141) happens when casting between incompatible character sets. Convert to utf8mb4 before casting to JSON.
Missing quotes, commas, or braces make the source text unparsable.
Casting a latin1 string containing multibyte UTF-8 breaks JSON encoding rules.
Numbers, dates, or binary blobs cast directly to JSON without conversion raise the error.
Tabs, line breaks, or 0x00 bytes inside the string invalidate JSON syntax.
Raised on insert/update when JSON text is invalid at position N. Fix by correcting the JSON string.
Occurs when a JSON column uses a non-utf8mb4 charset. Alter the column to utf8mb4.
Appears when a JSON path expression is syntactically wrong. Review the path syntax.
Triggered when a JSON value exceeds the max size. Compress or split the data.
No. MySQL stops the statement before writing invalid JSON, so your original data remains unchanged.
No. You must supply valid JSON. Use JSON_OBJECT or escape problem characters.
Upgrading will not fix malformed data, but newer versions add JSON_VALID, CHECK constraints, and better diagnostics to help catch issues earlier.
Galaxy's editor highlights invalid JSON strings and its AI copilot auto-generates JSON_OBJECT queries, reducing casting errors during development.
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