API Platform version(s) affected: 4.0.17

Description

We have a complex but well maintained project since 2019. We never have any problem with the major upgrades w/ MUI, react-admin nor w/ the React. But the upgrade to the React 19 and MUI v6 seems impossible. After I solve every errors and breaking changes on console and in the code I got this all the time:

What is happening when this loading page is occurring? What the program waiting for exactly? It seems, the API is reachable and it gives all required information.

or

After a while, I realized that, if I install this project from scratch it fails the same way. I installed as the docs said. The code can be downloaded below.

my-admin.zip

I do not know what causing the problem; the react 19 or the MUI v6 or something else.

How to reproduce

1. Install the app by the docs info.
2. Run the project
3. See the never-ending circular loader...