If you check your debug logs you have the error:
Error: Failed loading settings file:
bitcoind_1 | - Unable to parse settings file /data/.bitcoin/settings.json
To resolve, first connect to your Umbrel device by following the instructions in How to SSH into Umbrel on a Raspberry Pi or by accessing a terminal on your Linux machine here: Official Umbrel Troubleshooting Guide and FAQ
This command is the quickest way to resolve the error, by deleting the file first:
rm ~umbrel/app-data/bitcoin/data/bitcoin/settings.json
Then you should restart Bitcoin:
~/umbrel/scripts/app restart bitcoin
If for any reason when attempting to delete the file you face a permission or other errors that prevent you from doing so, we can also edit the file with this command (performing this step has been more reliable then attempting the file deletion which often returns a permission denied error)
Run this command to edit/create the file:
sudo nano umbrel/app-data/bitcoin/data/bitcoin/settings.json
Then it will take you to a blank file and just type and add two lines like this, with the two curly braces
{
}
then hit CTRL+X to exit, Y to save, and enter to continue.
After completing the edit don’t forget the last step of restarting Bitcoin:
~/umbrel/scripts/app restart bitcoin
You can run that restart bitcoin command or within your Bitcoin Node app you can also click Save and Restart Node in Advanced Settings on the top right.
Upon restarting wait ~5 minutes and this will resolve the error with the settings.json file.