The error appears when you insert or update text that contains characters not representable by the column’s character set or collation.
MySQL “Incorrect string value” occurs when text contains bytes not representable in the target column’s character set, typically UTF-8 vs. latin1. Convert the column (or connection) to the correct UTF-8 charset to resolve the issue.
ERROR 1366 (HY000): Incorrect string value: '\xF0\x9F\x98\x8A' for column 'name' at row 1
MySQL raises the “Incorrect string value” (error 1366) when it cannot store incoming bytes with the column’s current character set and collation.
The database engine validates every byte sequence against the column definition and aborts when it sees an invalid code point.
The error often surfaces during INSERT or UPDATE statements that involve emojis, accented characters, or any multi-byte UTF-8 sequence while the table or connection is still using latin1, utf8 (3-byte), or another limited encoding.
Developers hit this error after migrating data, importing CSV files, enabling new Unicode features, or receiving user-generated content containing emojis.
It can also appear in replication when source and replica have different character sets.
Leaving the mismatch unresolved blocks data writes, breaks applications, and risks silent truncation if sql_mode is not strict. Correct encoding ensures data integrity, search accuracy, and consistent analytics downstream.
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The application sends 4-byte UTF-8 data, yet the target column only understands single-byte latin1, triggering the error.
Standard utf8 in MySQL cannot represent code points above U+FFFF such as emojis, causing failures on insert.
Foreign-key relationships can reject inserts when referenced and referencing columns differ in charset/collation.
CSV or dump files encoded in UTF-8 are read as latin1, creating illegal byte sequences in the resulting queries.
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Run SHOW FULL COLUMNS and ensure the Collation ends with utf8mb4; any other charset cannot store 4-byte Unicode like emojis.
Yes, encode the data on the client side to a charset the column already supports, but this often leads to loss of characters.
Minimal impact for InnoDB; index size grows slightly. Proper collation helps maintain query speed.
Galaxy’s SQL editor highlights charset mismatches in real time and its AI copilot suggests correct ALTER statements, reducing trial-and-error.
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