Error on pre-update check for Joomla 5.1

Question

In preparing to upgrade from Joomla 5.0.3 to Joomla 5.1.0 I open the Joomla Update page.

While running the (automatic) pre-update check I get this error:

An error has occurred while fetching the JSON data: HTTP 500 status code.

— in a red box at the top of the page.

I have not had this error before on updating from one version to another.

I would be grateful for pointers on where the error comes from and how to get rid of it.

Thank you!

Answer 1

Check the network tab in your browser's dev tools - this should show you the failing request and some more information on what exactly is failing.