If you connected your Trezor wallet to Metamask or Nifty and got this error: “EthQuery - RPC Error - Error. Forbidden key path” it is because the last Trezor firmware version is not compatible with Nifty or Metamask.
To make it more clear, you should have installed version 2.3.0 in model T or 1.9.0 in Trezor One.
If this is your case, in order to make it work, you should downgrade the firmware to version 2.3.0 in Trezor model T or 1.9.0 in Trezor One.
Here are the instructions on how to do it from Trezor’s wiki:
1. Visit https://wallet.trezor.io and connect your Trezor.
2. Type "custom_firmware" after your Trezor device ID in the URL.
(Trezor Wallet generates a unique ID which is shown in the URL address after the Trezor device is connected in Trezor Wallet. This ID provides a unique identifier so JavaScript can address more than one otherwise completely equivalent devices. This ID is regenerated on every Trezor initialization, so it can not be tied to a person and it is not shared via any servers).
3. Download the needed firmware version (.bin file) from the Trezor Github repository (Trezor One, Trezor T) and click on "Choose File" to upload the FW file.
https://github.com/trezor/webwallet-data/blob/master/firmware/1/trezor-1.9.0.bin
https://github.com/trezor/webwallet-data/blob/master/firmware/2/trezor-2.3.0.bin
4. Trezor Wallet now prompts you to initiate the firmware update process. Follow the instructions to load the firmware file on the device.
It is not possible to downgrade the firmware on Trezor One once certain firmware has been installed.
Check the original wiki article for further information and downgrade options table.
Finally, in the link below you will find information on how to access the Money on Chain platform and set up your wallet: