Option 1: Switch your wallet to a different blockchain and then switch back to the original.
Try to switch your wallet to a different blockchain and then switch back to the original one to see if the error is fixed.
Option 2: Change your blockchain rpc endpoint to a custom one.
Go to Settings > Network > The network you are using > New RPC URL. Paste the custom rpc endpoint into the text box. You can find the public available rpc endpoints on ankr public rpc.
If you are still having problems, please contact our support for help.