nondeterministic collations are not supported for operator class “…”

SQLSTATE 0A000 condition feature_not_supported class 0A — Feature Not Supported severity ERROR

Reproduced & verified on PostgreSQL 14.23, 15.18, 16.14, 17.10 and 18.4 — identical message on every version.

Last reviewed 4 Jun 2026 · Reproduced live with the SQL on this page.

Symptoms

A statement failed with SQLSTATE 0A000 (feature_not_supported), reported at severity ERROR. This is a Feature Not Supported condition: PostgreSQL emits the message nondeterministic collations are not supported for operator class "…".

The client receives SQLSTATE 0A000 (feature not supported).
The operation is rejected at ERROR level; the statement does not complete.

What the server log shows

ERROR:  nondeterministic collations are not supported for operator class "…"

Why PostgreSQL raises this

Class 0A (Feature Not Supported) means the statement was syntactically valid but asked for an operation this server does not implement, or that is not allowed in the current context.

As described in PostgreSQL’s Appendix A PostgreSQL Error Codes, SQLSTATE 0A000 carries the condition name feature_not_supported in class Feature Not Supported. (Paraphrased — see the linked reference for the exact wording.)

Common causes

Using a SQL feature or option not implemented by this PostgreSQL version.
Attempting an operation disallowed in the current context (e.g. inside a transaction block).
Combining clauses that PostgreSQL does not support together.

How to fix it

Rewrite the statement to avoid the unsupported feature.
Check the version notes — the feature may exist in a newer release.
Move the operation outside the disallowed context if applicable.

Version applicability

This message is present in PostgreSQL 15, 16, 17, 18 and 19.

Related & next steps

Reference: PostgreSQL Appendix A PostgreSQL Error Codes.