I was able to solve this problem with this somewhat hard to find gem: https://central.owncloud.org/t/no-basic-authentication-headers-were-found-message/819
I was unaware Nextcloud prefers mod_php and not fastcgi
in case link goes down…
Solution
There is no “all in one” solution but you can try to add this to your Apache vhost configuration:
SetEnvIf Authorization “(.*)” HTTP_AUTHORIZATION=$1
before the line “ProxyPassMatch”.
For mod_fastcgi a possible solution is to add this to the Apache config:
FastCgiConfig -pass-header Authorization