I have run into very big and strange problems…
My site was almost ready, so I decided to move it from Directory to Root of Subdomain…
First, I deleted another Grav installation, which was originally in Root, so I deleted that, and Moved everything from my Directory to Root…
Now…
subdomain. myname. com - is Not Responding at all, giving me Error: The page is not redirecting correctly, it may be caused by blocking cookies…
subdomain. myname. com/admin - is loading my Template with 404, no such a page (admin) was found…
Then, as a Test - I tried again to load:
subdomain.myname. com/Directory/admin (there are Zero files now) - However - it Loaded a Broken Admin - and I was even able to Log in (into Non-existing Admin )
Also I should note - my website is on Cloudflare - I don’t know if it may cache something in a crazy way…
I can’t access my website now, neither in front, neither in Admin…
Not a server expert here, but sounds like you subdomain setup and/or .htaccess are misconfigured. Usually subdomain points to some directory, but that’s not the case from what you’re describing. So I’d start checking server setup first.
Another option - save your /user folder, install fresh Grav on root, replace /user folder there with yours. If that won’t work, I’m pretty sure it’s the server/htaccess config issue
Subdomain points to Subdomains directory;
I have 14 other subdomain websites which all are going well;
I moved the site from subdirectory . myname .com / h1 folder to subdomain root subdirectory. myname .com root folder.
I suspect in the Grav configurations there might be some place where it is configured that H1 is my root installation directory and not otherwise.
So again I would suggest just do a fresh install to the folder you want, see if that works and if it does, just replace the /user folder. There should be no references in configs to the exact folder. I had moved once whole Grav CMS one folder deeper and there were no issues 
I did the same thing, I made a fresh install of Grav & Admin, created a new user as it requested;
I copied over all old user / pages, plugins, templates, user/config/ plugins…
Cleared cache in Admin, all well…
then I decided to change user/system.yml file - everything crushed with “can not redirect properly”
Wouldn’t it be reasonable to check which exact change in system.yml breaks it?
OK, I re-uploaded the Old One again…
Then I went to user/system.yml and deleted everything there to Empty it…
Then the Site & Admin loaded all well…
My Theme was the default Quark again…
So, I changed Theme to Bootstrap4 again, then all my staff loaded…
BUT - I am not sure about my settings, probably my settings are gone and I should re-check most settings… I had no time yet to go through everything in settings.yml to tell what exactly makes this…
Solution:
Yes, like I suspected,
system.yml had a setting:
custom_base_url: ''