We've defined error.message in #1992 as a replacement for feature_flag.evaluation.error.message.

It turned out to be problematic to come up with requirements on when to use it vs exception.message - #2296

It's also somewhat confusing when it comes to logs (is error.message related to log body with error severity).

So error.message is very generic. Unlike error.type it's not intended to be used on metrics or span -> metrics pipelines and the benefit of unification of error messages across domains is not huge.

At the same time, domain-specific error messages look more descriptive. Some candidate

• (g)rpc.response.status_description as a companion of rpc.response.status_code using domain-specific terminology
• http.response.reason_phrase
• feature_flag.error.message - can be documented as precisely as needed. This is also the only domain where error.message is used.

Based on the discussions in logs sig, we're proposing deprecating error.message and replacing it with domain-specific attributes.

/cc @open-telemetry/specs-logs-approvers @open-telemetry/semconv-feature-flag-approvers