ulysses9994573 please check your log files in <flarum>/storage/logs and/or your webserver logs.

I'm splitting your post into a new support discussion so we can better help you.

    I check the log,
    [Wed Dec 04 01:23:55.722435 2019] [core:error] [pid 4756:tid 1724] [client 1**.4*.*.***] AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.
    I think I don't know how to do that，and
    Page redirect error is the most important things
    It brings me to the localhost.

      I allow Flarum to use htaccess file, and I didn't customize anything that in htaccess, It used working and now I don't know what happened. Should I customize something in htaccess?

      It can successful loading in my server but shows 500 in other places. One more thing I still thanks you can help me to solve this problem.

      First time i think is the apache server do not allowed me connect but I put a test page it can work, now I have no ideal.

        ulysses9994573 is it an "oops something went wrong" 500 error (generated by Flarum) or generic "500 error" (generated by the webserver) ?

        If the only error you get is the internal redirects issue, then it's likely a misconfiguration in apache configuration somewhere, maybe something to do with your http->https redirects or something like that.

        Flarum's htaccess defines a single rewrite that shouldn't cause any issue by itself. No change should be required to Flarum's htaccess file.