Quicken error CC-800 can occur due to various reasons. To resolve this issue, go with the following steps: 

1. Update Quicken: Ensure the latest version; go to Help > Check for Updates.

2. Refresh account information: Open Quicken, select the account, click the gear icon, and "Update Now." Enter bank credentials and update.

3. Validate and repair Quicken file: Go to File > File Operations > Validate and Repair. Check "Validate file" and click "OK." Review data_log.txt and fix issues.

4. Deactivate/reactivate accounts: Go to Tools > Account List, click "Edit" for the account, and "Online Services." Deactivate, confirm, and click "OK." Close and reactivate.