Could you check if currently assigned defalult layout is valid in the CMS?
Check library paths ie
for CMS in CMS settings -> library path, it needs to be fully qualified path, please see ‘Library Location’ section of this post - Ticker RSS Custom Tag
For player, it would be probably best to leave it in the default path and see if that helps, default ie
C:\Users\<USERNAME>\Documents\Xibo Library
Could you also please open php.ini, find this line
always_populate_raw_post_data -1 and make sure it’s not commented out (no ; before that line in php.ini)
restart your web server after this change.