Your software
My Mautic version is: 5.0.4
My PHP version is: 8.1
My Database type and version is: 10.11.6
Your problem
My problem is:
Form action url should start with https, but start with http generated by mautic, my mautic site URL already set to https://, how to change it?
There is not this problem In Mautic 4.4.12, all works fine.
Can you show example what is in your var/log folder to understand why mautic doens’t work? Is the problem, that mautic has no writing access to the cache folder?