Roundcube login error "Plaintext authentication disabled" - solution

OS type and version Ubuntu 22.04.4
Webmin version 2.105
Virtualmin version 7.9.0
Related packages SUGGESTED

After working on a new server a few days i cannot login into Roundcube anymore - always get the error “Ungültige Anfrage” - in the logfile of roundcube (/var/log/roundcube/error.log) i found “Plaintext authentication disabled. in /usr/share/roundcube/program/lib/Roundcube/rcube_imap.php on line 211”.

This error seems to be since years - go to /etc/dovecot/conf.d/10-auth.conf and change the line
#disable_plaintext_auth = yes
disable_plaintext_auth = no
Don’t forget to uncomment. Than a /etc/init.d/dovecot restart and everything works again.

I hope I can give some guys a fast solution for this error.

1 Like

Which Roundcube version?

Roundcube 1.5.0

Thats default on my OS.

Line 11 was missing here, only Line 10 was like yours

Thanks for the info. I am currently on v1.6.6 (having upgraded from v1.5.6 LTS)

I am also on Ubuntu 22.04.4 (Roundcube v1.5.0 doesn’t seem to be an option under Install Scripts) except under “Unsupported”

Edit: I should also add that I am on the latest version of Virtualmin (7.10.0)

Must be a OS thing. I’ve never touched that.
During install script there is a question about plain text or encrypted, not sure if it is related.
I always select plain text.

One important difference: we install Roundcube systemwide, so not with the scripts. Why? Because in this case the Server is only a Mailserver and we don’t want to install roundcube on every single domain (because of to many instances). One serverwide redirect to

You do know that even with script, a user from a different domain can still use the authentication from that other domain. Its authenticating to the mail server not the domain its in. So still systemwide.

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