Plesk is not accessible: Failed opening required 'auth.php'

Aleksandar Stoev

Updated January 13, 2026 19:12

DoNotDelete:docref Plesk for Linux kb: technical ABT: Group B

Applicable to:

After a Plesk installation or a Plesk upgrade, the following error is shown on the login page:

CONFIG_TEXT: Warning : Unknown: failed to open stream: No such file or directory in Unknown on line 0

Missing symbolic link /usr/local/psa/ -> /opt/psa/

Connect to the server using SSH
Remove the link /usr/local/psa if there is any:

# unlink /usr/local/psa
In case of error unlink: cannot unlink '/usr/local/psa': Is a directory rename the directory directory /usr/local/psa :

# mv /usr/local/psa{,.bak}
Create a symbolic link /usr/local/psa/ -> /opt/psa/:

# ln -s /opt/psa /usr/local/psa
Reinstall Plesk updates as described in the article How to update Plesk

This however, won't work if Plesk version is already the latest. In this case, navigate to http://autoinstall.plesk.com or http://origin.autoinstall.plesk.com/pool/ , download the respective version of the plesk-core package and install it using dpkg/rpm. For example:

# wget http://autoinstall.plesk.com/PSA_18.0.37/dist-deb-Debian-10.0-x86_64/base/plesk-core_18.0-v.debian.10+p18.0.37.1+t210802.1246_amd64.deb && dpkg -i plesk-core_18.0-v.debian.10+p18.0.37.1+t210802.1246_amd64.deb