Migrate your website to MainHoster.deWithout downtime and without data loss

Published on October 20, 2026

The right order

The most common mistake when moving is switching the domain first and transferring the data afterwards. Then the site is offline for as long as the move takes - and mails arriving during this time end up nowhere.

The right way is the reverse order:

1. Order the web hosting
2. Transfer files and database
3. Transfer mailboxes
4. Test the site via a preview address
5. Switch the domain or change DNS
6. Only end the old contract after that

Step 1: Take stock at the old provider

Before you touch anything, collect these details:

• FTP or SFTP access (host, user, password) at the previous provider
• Access to database management, usually phpMyAdmin
• A list of all email accounts with passwords
• Where the domain is registered - with the previous host or with a separate registrar?
• The PHP version used by the existing site

Also take a complete backup at the old provider before you start. It is your fallback option if something goes wrong along the way.

Step 2: Transfer files and database

In Plesk, the Website Importing feature is available for this. You enter the credentials of your previous host, and the files are copied directly from server to server - without the detour via your computer. With larger sites, that is much faster than a manual download and upload.

The manual route works just as reliably:

1. Download all files from the old server via FTP.
2. Back up the database in phpMyAdmin via Export as an .sql file.
3. In Plesk, create a new database including a user under Databases (see Create a database).
4. Import the .sql file into the new database via phpMyAdmin.
5. Upload the files via FTP into httpdocs.

With large databases, the import can fail at the upload limit. The maximum upload size can be raised in the domain's PHP settings - in plan S to up to 10 MB, in L and XL to up to 100 MB. If the address structure changes at the same time as the move, set a 301 redirect for every old address - otherwise the rankings you have built up are lost.

Step 3: Adjust the credentials

After the import, your site's configuration still points to the old database. So adjust the credentials:

• WordPress: in wp-config.php, the values for DB_NAME, DB_USER, DB_PASSWORD and DB_HOST (usually localhost).
• Joomla: in configuration.php.
• Your own applications: in the respective configuration file or environment variables.

Also check in Plesk whether the same PHP version is set for the domain as at the old provider. An older site on a much newer PHP version can otherwise fail with error messages - how to switch it is described in the guide Change the PHP version.

Step 4: Take over email accounts

For the mailboxes, Plesk offers the email import. It transfers the existing messages via IMAP from the old server, so folder structure and history are kept.

The process: create the accounts under the same addresses in the new web hosting, start the import with the old credentials and wait for the transfer to complete. Only then switch the domain - otherwise mails arriving during the move are lost. More on this in the guide Set up email accounts.

Step 5: Test before you switch

As long as the domain still points to the old server, you can open the new installation via the preview function in Plesk. Check specifically:

• Does the home page load and do subpages work?
• Are images displayed - or are they missing because absolute paths still point to the old domain?
• Do forms and the backend login work?
• Do PHP error messages appear that point to a wrong PHP version?

Only once everything runs cleanly here do you move on to the domain.

Step 6: Switch the domain

Now you switch the domain - either via a complete domain transfer to MainHoster.de or by changing the nameservers or A records at your previous registrar. Both routes are described in the guide Connect a domain to your web hosting.

Allow for a transition phase. Depending on the TTL setting, DNS changes take a few hours until they have arrived everywhere. During this time, some visitors still land on the old server. Therefore: only cancel the old contract a few days later, not immediately.

Finally, set up the SSL certificate - without a valid certificate, the browser shows a warning. The guide Set up an SSL certificate shows how to do that with Let's Encrypt in a few clicks.

Frequently asked questions