Aug 22, 2022

Roundcube webmail most common errors + solutions!

Need solution for your error in Roundcube webmail? We show you all errors with the solutions included!

Roundcube webmail most common errors + solutions!

In this article, we’ll explain you the most common Roundcube webmail errors all the way through. We’ll tell you what the problem is and more importantly, what you should do to fix the error!

What is Roundcube webmail?

Roundcube is a software package that serves as a webmail . A webmail is a web page that ensures that your emails are loaded via the IMAP protocol and you can view them in the webmail / web page. Sending e-mails in the webmail is via SMTP.

This way, you don’t have to use a full-fledged e-mail program to check your e-mail, but you can quickly and easily log in to your e-mail via Roundcube from anywhere in the world. So if you’re on vacation, you can use your laptop, tablet or even mobile phone to quickly log in to your email.

Roundcube is written in the PHP programming language and works with a MySQL database. Thus, Roundcube can be installed on virtually any web server and you can easily and quickly create your own webmail and host it on a hosting package.

Error messages in Roundcube

Below I list the most common error messages in Roundcube that can occur when you use it. With each error message, I explain what the issue is, but also what the solution is so you can fix it quickly and easily.

All error messages in Roundcube

  1. Connection to storage server failed
  2. [Connection error (Failed to reach the server) ](#connection-error-failed-to-reach-the-server “Connected error (failed to reach the server)”")
  3. Your session is invalid or expired
  4. Unable to perform operation- no free disk space

Connection to storage server failed.

The roundcube installation often tries to connect via the IMAP protocol over port 143 (without SSL) or 993 (with SSL) to the underlying IMAP server. The IMAP server that you have set up in the MX DNS records of your domain name does not respond to the login attempt. It is also possible that it does respond, but does not give the desired response that roundcube has been waiting for.

Solution: Connection to storage server failed.

First of all, you can check via an online TCP check whether your domain name responds to the IMAP ports. You can do this by going to the following link :

Here you enter your domain name followed by :143 or :993.

Example entry: or

The tool will now test if port 143 or 993 (IMAP ports) are open and if there is a response.

I see: Connection timed out

If there is no response it could be that your email provider has an outage, or that your domain name is not properly linked so that your email / IMAP server is not working properly,

In case of a Connection timed out I advise you to always contact your e-mail or hosting provider.

I see: Connected

If it says connected but you still experience the error message in roundcube, then I suspect that there is a failure with your email or hosting provider. Also in this case, I recommend contacting them so they can check what’s going on!

Connection Error (Failed to reach the server)!

This error amounts to the same thing as the previous error above. I advise you to implement the same solution so that your webmail will soon be working as you are used to!

Your session is invalid or expired

Roundcube keeps php session records when you are logged in and thus checks if the maximum time you are logged in has not yet expired.

If that is the case, this error message is shown and you have to log in again, after which you can stay logged in for a while.

If you receive this error message immediately after logging into Roundcube, then Roundcube is unable to create a php session file, and something is often wrong or broken on the web server where Roundcube is hosted.

Solution: Your session has expired or is invalid

In this case, I recommend that you first check Roundcube’s configuration and where Roundcube stores the session files.

In the following file, you will find some configuration rules for your sessions: config/

// Session lifetime in minutes
$config['session_lifetime'] = 30;

// Session domain:
$config['session_domain'] = '';

// Session name. Default: 'roundcube_sessid'.
$config['session_name'] = null;

// Session authentication cookie name. Default: 'roundcube_sessauth'
$config['session_auth_name'] = null;

// Session path. Defaults to PHP session.cookie_path setting.
$config['session_path'] = null;

The session_lifetime is the previously named length of time before your login session expires. You can further increase or decrease this as you wish.

The session_path is the path where the sessions are stored. I advise you to leave this empty so it follows the general session_path of PHP.

If the error message does not disappear and appears immediately after logging in, then the web server cannot store a session in the default PHP session path. I then recommend you contact the email or hosting provider with this information.

Unable to perform operation. No free disk space

The error message actually says it all. There is not enough free storage space to complete and process your operation.

Suppose you compose an e-mail or want to answer an e-mail, the IMAP server creates a draft. This concept of course costs storage space and unfortunately there is none left.

This is why the error message you are experiencing now, clearly indicates that the storage space of your own e-mail address on the IMAP server is full.

Unable to perform operation. No free disk space

In this case, I recommend that you first empty your Recycle Bin within Roundcube to make space. This will free up space immediately if the Recycle Bin still contains items and the error message should also disappear immediately.

If the Recycle Bin is already empty, then I recommend that you go through your inbox and see if there are any emails with large attachments that you no longer need to keep. You then discard these and empty the Recycle Bin immediately afterwards so that the space is actually freed up.

Increase email account storage space

Several control panels at email or hosting providers allow you to set the storage space of your email address. I will explain how to do this for each control panel:

  • DirectAdmin: In this control panel you go to the heading Email accounts. Then you will see your email accounts are listed there. You click on modify and then you get a page where you can change your password, but also specify a new quota.

You enter the new quota after which it will immediately become active and the error message in Roundcube should be solved!

  • Cpanel: You click on the heading Email accounts. Then click on the link Disk and Quota for your e-mail address.

A new page will open where you can set your new e-mail quota. After this, the error message in Roundcube should be resolved and you should be able to continue.

  • Plesk**: Here you log into Plesk and click on subscriptions. Select your domain name and click on Customize. A resource tab will open where you can set the mailbox size. This will be your new e-mail quota.

After adjusting the settings, Roundcube should work again immediately and your error message will be solved.


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