conversion from wchar_t to server encoding failed: the OS error

Symptoms

A statement failed with SQLSTATE 22021 (character_not_in_repertoire), reported at severity ERROR. This is a Data Exception condition: PostgreSQL emits the message conversion from wchar_t to server encoding failed: the OS error.

• The client receives SQLSTATE 22021 (character not in repertoire).
• The operation is rejected at ERROR level; the statement does not complete.

What the server log shows

ERROR:  conversion from wchar_t to server encoding failed: the OS error

Why PostgreSQL raises this

Class 22 (Data Exception) is raised at run time when a value cannot be represented, converted, or processed by the requested type or function — bad input syntax, out-of-range values, or invalid arguments.

As described in PostgreSQL’s Chapter 8 Data Types and Appendix A (PostgreSQL Error Codes), SQLSTATE 22021 carries the condition name character_not_in_repertoire in class Data Exception. (Paraphrased — see the linked reference for the exact wording.)

Common causes

• A literal or parameter does not match the target type’s input format.
• A value exceeds the range or length the type allows.
• A function received an argument outside its valid domain.
• An encoding, cast, or format conversion failed.

How to fix it

1. Validate and sanitize the input value before sending it.
2. Cast explicitly to the intended type and confirm the format.
3. Widen the column/type or clamp the value to the supported range.
4. Reproduce with the exact literal to see which value is rejected.

Version applicability

This message text is present in PostgreSQL 15, 16, 17.

Related & next steps

• SQLSTATE 22021 — Character Not In Repertoire (full reference)
• PostgreSQL error code index

Reference: PostgreSQL Chapter 8 Data Types.