The JSON path string is encoded in a character set other than utf8, so MySQL rejects the statement.
MySQL error 3148 ER_INVALID_JSON_PATH_CHARSET occurs when a JSON path string is not utf8. Force the connection and all path literals to utf8mb4 to resolve the issue.
ER_INVALID_JSON_PATH_CHARSET
MySQL returns error 3148 when a JSON path expression supplied to functions like JSON_EXTRACT, JSON_SET, or JSON_REMOVE is not encoded in the utf8 family. The server only accepts utf8, utf8mb3, or utf8mb4 encodings for JSON path literals. If the path uses a different character set, MySQL rejects the statement.
Because JSON path expressions are parsed by the server, their character set must match the internal utf8 requirement. This rule was introduced in MySQL 5.7.8 when native JSON support landed. You will see this error most often after copying SQL snippets across tools that silently change encoding.
Non-utf8 client connection settings, mixed-encoding scripts, or literal path expressions stored in non-utf8 columns trigger ER_INVALID_JSON_PATH_CHARSET. The server detects the mismatch and aborts the query instead of silently mis-interpreting path bytes.
Legacy tables defined with latin1 or other 8-bit character sets often store path strings that later feed JSON functions. When those values are read, the runtime character set is inherited from the column, leading to error 3148.
Set the client and connection character sets to utf8mb4 before executing statements that contain JSON paths. Convert literal path arguments to the utf8mb4 character set using CAST or CONVERT if needed. For stored data, ALTER the column to utf8mb4 or wrap the value in CONVERT().
Once all path expressions are utf8, the same JSON function executes without error.
Dump and restore workflows that move data between servers with different default charsets frequently hit ER_INVALID_JSON_PATH_CHARSET. Always include --default-character-set=utf8mb4 in mysqldump and mysql client commands to keep encoding consistent.
In application code, use parameter binding instead of string concatenation to ensure drivers send utf8mb4 data. Confirm the connection collation with SHOW VARIABLES LIKE 'character_set_connection'.
Standardise on utf8mb4 for all schemas, tables, and connections. Enforce it in CI pipelines by rejecting migrations that create non-utf8 columns. In Galaxy, workspace-level connection templates default to utf8mb4, protecting engineers from accidental mismatches.
Error 3153 (ER_INVALID_JSON_CHARSET) fires when JSON documents themselves are not utf8 encoded. Error 3140 occurs when a JSON path syntax is invalid. These share similar root causes and can be resolved by verifying encoding and syntax.
When the path expression string literal is encoded in latin1, MySQL throws error 3148.
If the client or driver negotiates a different character set, all string literals inherit that encoding and fail.
Selecting a path from such column and feeding to JSON function triggers the error.
JSON document itself is not utf8 encoded.
The path string has illegal tokens or missing delimiters.
Occurs when mixing aggregated and non-aggregated columns; unrelated but often seen in the same refactor sessions.
Yes. The server accepts utf8, utf8mb3, and utf8mb4 for JSON path strings. utf8mb4 is recommended for full Unicode support.
Only path expressions. JSON documents themselves trigger error 3153 if not utf8.
MySQL converts data automatically when possible. Always back up before altering to avoid surprises.
Galaxy sets utf8mb4 on every connection template and surfaces charset mismatches during query linting, preventing errors before execution.
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