Custom GPT Connector POST Endpoints Fail Silently After GPT-5 Rollout

GPT builders Plugins / Actions builders
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Sometime around the time of the GPT-5 rollout, all POST (write/action) endpoints in my MCP-compliant Custom GPT connector fail silently—the allow/deny modal does not appear, and no requests reach my backend. I have tested with a VALIDATED minimal OpenAPI 3.1.0 schema, public HTTPS server, and required /fetch and /search endpoints. This behavior did not occur prior to GPT-5 rollout.

  • Both GPT-4o and GPT-5 models tested, same result.

  • Backend sees no incoming POST call.

Any GET operations work fine… but nothing trying to POST ever leaves the GPT.

This problem occurs on all my custom GPTs

I am a newbie kinda, so it may be something I’m doing wrong.

Thanks!

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It’s not your fault. Everyone is in SHOCK… Follow this thread: Custom GPT OAuth stuck on “Talking to <domain>” ,looking for official guidance

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You’re not doing anything wrong. It’s a known issue. Fortunately I got someone from openAI support to respond so it’s now officially on their radar. It was something about the agent “fix” they rolled out Friday night. At least we’re finally on openAI’s radar so something should get escalated and resolved soon.

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Has any one yet heard when connectors (e.g. HubSpot for read-only CRM data) will be available inside Custom GPTs?

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