This is a small list of some items that can cause an error. These items are the most common often forgotten about issues.
Enable Contracts/Blind Signing on Ledger
If you recently updated your Ledger device, the update may disable your Blind Signing (previously known as Enable Contracts). Please check your Ledger Ethereum App and make sure Blind Signing is enabled.
Hardware Wallets + Metamask not working on Site
Metamask's most recent updates on EIP-1559 created some issues with Metamask and Hardware Wallets. For Ledger please make sure you are on the latest version of Metamask and Ledger firmware is 2.0 or above. Metamask has not resolved this issue with Trezor. Please see this page for more information and other methods to use Trezor on site.