https instead of http since update to 2.26 (from 2.22)

[MarCol]

Hi,

I have just updated Mantis from 2.22 (somewhen in 2019) to 2.26 (a few weeks ago.
I have done that based on the tipps for the update.
Everything seems to be fine, without one thing:
When I receive an E-Mail, that there is a new bug or an update in a bug, then there will be shown the "wrong" link: "https://mantis.domain.abc/..." instead of "http://mantis.domain.abc/...
The domain is not a https, but only a http.
In the version 2.22, that worked correctly and fine. But why in this new version not?

The brings an error, opening in the browser until the "s" was removed in the address-line. Then it works.

Where can I change that?

Thanks a lot.

Regards, Marco