1) You could be getting this error because you haven't installed the polkadot.js browser extension. If you haven't, you can do so here.
2) Make sure your extension is set to allow use on any chain.
3) Go to manage website access and make sure that apps.karura.network is allowed.
Unable to retrieve keypair
1) You could be getting this error because you are trying to use a wallet that isn't supported. Ledger wallets will not work even if used with the polkadot.js browser extension.
2) Additionally, users with the other active wallet extensions sometimes receive errors. Once you disable the other wallet extensions, the error should go away.
3) Make sure your polkadot.js browser extension is set to allow use on any chain.
1010: Invalid Transaction: Inability to pay some fees, e.g. account balance too low
1) The amount you are trying to transact may be too much. Try using a little less and reinitiating the transaction.
2) You could be trying to pay your transaction fees with a token that is not supported. Only tokens that are traded on the DEX can be used to pay transaction fees. If you switch to pay your fee with a supported token, your transaction should process.
1010: Invalid Transaction: Transaction has a bad signature
Refresh the app and accept the metadata update. Refresh the app again.