Message activation fails occasionally

[BFU]

Hello everyone,

I´m facing a weird behaviour, where “occasionally” my self managed connector runtime fails to activate/correllate a message:

"Activity[severity=INFO, tag=NoMatchingElement, timestamp=2026-05-07T09:32:02.351965681Z, message=No matching activation condition. Not discarding unmatched email: AAMkADEzMTlhODM4LWJhM2QtNDI2Ny04NWY1LTA5ODNmYTBhNzk3OABGAAAAAAB5VqtnJtWLQrN4T_IvsztBBwD2MZcc9q_GSr5wlq7SF0lpAAAAAAEMAAD2MZcc9q_GSr5wlq7SF0lpAAAKb-WGAAA=, data={}, healthChange=null]"

This is from the inbound Office 365 Mail connector. It´s weird because this occurs in a send-receive-mail-loop, and the correllation/activation works fine for 3-4 mails and then just randomly fails.

My inbound connector has no activation condition and only has a correllation key which does match (i checked it manually).

If I send the mail again, in the same conversation, at some point it gets activated/correllated.

I´ve attached my model.

gatherOrderProcessDataProcess.bpmn (51.2 KB)

What could be the source of this behaviour? Is this a bug? It´s really irritating and unfortunately messes up the send-receive-dynamic quite a bit.

[zee-bot]

This looks like a timing/race condition issue where the message arrives before the process instance reaches the intermediate catch event and opens its subscription. I found the following relevant resources:

• Message buffering and timing issues
• Microsoft 365 email inbound connector correlation troubleshooting
• Process variables not merging intermittently
• Message correlation working intermittently

Does this help? If not, can anyone from the community jump in?

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[BFU]

I´m quite sure that this is not a timing/race condition issue, since we´re dealing with actual mails here, that are being sent, received and answered. This takes at least a minute, so the engine has plenty of time to reach the intermediate catch event and open it’s subscription.

In fact I have observed this error occur despite operate showing the token at the catch event.

[Philipp_Ossler]

@BFU thank you for sharing the details. This sounds like a bug.

I recommend opening a bug issue on GitHub: Issues · camunda/connectors · GitHub