How do I fix timeout errors when trying to create a user auth token?

When creating a user auth token, after clicking ‘Create New Token’ the process does not complete and eventually a 504 gateway timeout error is shown.

This problem can be caused by incorrectly configured mail server settings.

Confirm that Matomo is able to send emails using the console command documented in Emails from Matomo are not being sent, how do I troubleshoot and solve the issue?

Follow the How do I send Matomo emails using SMTP server? guide and make sure the SMTP server settings are correct.

Previous FAQ: Why many of my visits have “0 Action” in Matomo and how do I fix this issue?