Can not release a new build in TestFlight

Hi i am getting since days the error in App Store Connect when I want to release a build for a test flight group:

"An error has occurred while processing your enquiry. Please try again later."

It was working for 2 years but since a few days not.

Do you have any ideas?

I answer this by myself:

the build no. must be higher than the production app version.

Can not release a new build in TestFlight
 
 
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