"could not deserialize/serialize JSON payload to table: bad argument #1 to '?' (string expected, got nil) while logging request" error on bodyless GET/DELETE Admin API requests with audit logging enabled

When audit logging is enabled, the following error messages are seen in the logs for GET, and DELETE Admin API requests;

2026/09/07 00:22:33 [error] 5417#0: *69428 [kong] audit_log.lua:232 could not deserialize/serialize JSON payload to table: bad argument #1 to '?' (string expected, got nil) while logging request, client: 127.0.0.1, server: kong_admin, request: "GET /plugins HTTP/1.1", host: "0:8001"

2026/09/07 00:23:55 [error] 5417#0: *71608 [kong] audit_log.lua:232 could not deserialize/serialize JSON payload to table: bad argument #1 to '?' (string expected, got nil) while logging request, client: 127.0.0.1, server: kong_admin, request: "DELETE /plugins/5392345b-3395-4236-b7e7-f62352159899 HTTP/1.1", host: "0:8001"

Why are these errors shown and how can they be fixed?

The audit log code (kong/enterprise_edition/audit_log.lua) only attempts to deserialize/log the JSON payload when a request body is actually present (payload ~= nil). Because of this, a bodyless GET or DELETE Admin API request that still carries a content-type: application/json header does not produce this error, and the request continues to be logged correctly in the audit_requests table.

If you do see this error on a bodyless GET/DELETE Admin API request with a content-type: application/json header, it is harmless — the Admin request is still logged correctly in the audit_requests table — and can be avoided by making the GET/DELETE requests without a content-type: application/json header.