Sometimes the issue isn't the software itself but corrupted Windows libraries that DAEMON Tools relies on, such as .dll files. License checking error - DAEMON Tools Forum

: If the standard uninstaller fails, use the DTCleaner utility to remove leftover registry keys.

The most common cause of "sign check" errors is the Windows 10 or 11 Driver Signature Enforcement policy, which blocks drivers that do not have a verified digital signature.

: Once your PC reboots to a list of options, press 7 or F7 to select "Disable driver signature enforcement."

: Go to Troubleshoot > Advanced options > Startup Settings and click Restart .

: Hold the Shift key while clicking Restart from the Start menu.

: Your PC will boot normally; attempt to run DAEMON Tools Ultra again to see if the error is resolved. 2. Configure Firewall and Antivirus Exclusions