www programming

Last night I moved my wordpress to the root directory and phpbb to the /forum directory.

I tried with Visual composer and it did not work...I tried it with another page builder and W3all worked.

The problem for me is my premium theme is built around visual composer. I cannot remove it.

So I guess this solution will not work for me unless there are some tests you would like me to do. I run my own server so I have access to all logs. I can't do any more testing until tonight.

should have this to see, as a 500 error do not let know too much: the server answer that a request has not been processed because not recognized in some way. But it is hard to understand why it come out without debugging what the code do while executed.
Consider that a modified version is installed and working here, it is used in the home with revolution slider (as you can see) for the cms logo slider. That's the unique page, done with Visual composer and rev slider (which i would like to remember, that are free GPL codes iquery snippets, adapted to build features in WP). An old version (4 years ago).
Hope something else about will come out in mind to resolve this ... in any new let know ..

I disabled all other plugins and Visual composer still won't load or I get 500 errors when trying to use the w3all plugin

No, unfortunately it appears this plugin interferes with Visual Composer. When I have W3all activated, Visual composer doesn't even load and I get a lot of 500 errors. When I try to edit the page, or when I try to load other pages. Some has the error others do not...I can try to disable other plugins to see where the problem is but after I disabled W3all, I was able to use Visual composer again.

Ok, on my site I have this

Wordpress: www.xxx.com/blog

phpbb: www.xxx.com/forum

and then .htaccess file in root that redirects traffic to /forum.

Tonight I will switch blog to the root
http://www.xxx.com/

and I will retest. Maybe the redirect is causing an issue..

On my test where old plugins are working partially, but working, all result ok, it is an old version of a premium theme which was including Visual Composer. It has been tested ok and is working ok on an online site, perhaps your error 500 come out due to some other reason or the latest version is substantially different from the old one i have, and change something that conflict. That result to me really strange but never say never.
Visual composer has been also tested ok directly here on this working test.
By the way i have not latest version. But in theory, really should work.