Some users have reported the "Unable to retrieve the key pair" error. Below you will find a list of ways to troubleshoot this.

1. Are you using a Ledger hardware wallet? 

Make sure your Ledger device is connected to your computer so polkadot.js can find the keys. 

2. Troubleshoot the polkadot{js} browser plugin

  1. Update your browser to the latest version. To do this click on the "Update" button on the top right and then restart Chrome.
  2. Go to polkadot.js. It's likely that you'll see a small "1" next to Settings. If that's the case, go to Settings > Metadata and click on "Update metadata".
  3. Then go to the Accounts page and try sending again.

If that doesn't work, please do the following:

  1. Open the extension and click on the gear icon on the top right.
  2. Click on "Manage Website Access". Is listed there and enabled?
  3. If it's not, try to enable it and then refresh the Accounts page and try sending again.
  4. If it's not clickable, then go back, click on the gear again and click on "Open extension in new window".
  5. Follow the same process to enable it.

3. Disable other extensions

If none of the above solved the issue, then there must be another extension interfering with the Polkadot extension. In order to troubleshoot this, disable them one by one and try again. 

Start with the Polkadot- and Crypto-related extensions to pinpoint exactly which extension is causing trouble.