Grafana after installation and restart: An unexpected error happened

If this is not the correct place for the question, please let me know. i’m unexperienced and didn’t find a better place! Thanks.

First of all my configuration:
Add-on: Grafana
The open platform for beautiful analytics and monitoring

Add-on version: 10.4.2
You are running the latest version of this add-on.
System: Home Assistant OS 15.0 (amd64 / generic-x86-64)
Home Assistant Core: 2025.3.4
Home Assistant Supervisor: 2025.03.3

After installation the logs says that no errors occured!

After restarting HA and starting grafana i get this error:

An unexpected error happened
Details:

TypeError: localStorage.getItem is not a function

cy@http://192.168.10.103:8123/api/hassio_ingress/1flGzTHyeF-BNZ4rsHb-RPbd09y2KHZ7M8foXY3X_eg/public/build/9890.2f086d4a8fdbd47b8d24.js:41:220079
yn@http://192.168.10.103:8123/api/hassio_ingress/1flGzTHyeF-BNZ4rsHb-RPbd09y2KHZ7M8foXY3X_eg/public/

I try to install grafana for several weeks. I did not find any hints for this problem.
PLEASE: Has anybody some hints for me?