Error 500, 502, 503, 504

An incorrect PHP version is activated

It's possible that a certain PHP module is required for the proper operation of your website, which is not present in the current version. How to change PHP version.

Another possible cause is that different PHP version are required for different websites. If that's the case, you need to deploy the two websites separately, on the two different hosting services, as the PHP version is valid for the entire account.

Website files are located at a wrong directory

All related files. If that's not the case, move the website files to the proper directory.

Incorrect file and directory

In most cases, the correct rights would be '755' for directories and '644' for files.
How to change the file and directory rights
What is file and directory rights

Errors in .htaccess

Invalid rules in .htaccess is one of the most common error causes. If you have made any changes to .htaccess by yourself, try removing those and test the website availability once again.

.htaccess files for the most popular CMSs

The maximum number of simultaneous processes is reached

There is a limit of 18 simultaneously running processes on the virtual hosting (see all limitations). When you reach this limit, new process cannot start and an error occurs.

Most often, this limit is reached due to CRON tasks, frequent connections from mail clients via IMAP protocol or other background processes.

You can find out the current number of running processes by connecting to SSH and implementing the command:

ps aux | grep [u]1234567 |wc -l

where u1234567 is your hosting login.

To solve this problem, try as follows:

  • increase the time interval between CRON tasks;
  • limit the number of IMAP connections in the mail client settings: IMAP connections limitation;
  • inspecting.

Still not working?

Contact your hosting support team. In the application, you need to specify:

  • the exact time, when the error was spotted;
  • the name of the website, on which the error occurred;
  • if the error does not appear immediately, but follows some actions (adding of an image, website form submission, file import, etc.), describe the detailed procedure so that we could produce the problem;
  • if there is a need for authorization in the administrative section of the website, in order to reproduce the problem, provide the relevant credentials (login and password).