54003: Invalid If-Match header

The specified If-Match header cannot be used for concurrency control.

• The value specified in the If-Match header is not a valid Sync object revision.

The value you provide should be a revision assigned by the Sync service when interacting with an object.

• In SDKs, this is the revision field, part of the object descriptor.
• When using REST (e.g. via the Twilio Helper libraries) this is the ETag header provided in responses.