Before changing complex settings, rule out basic Windows permission blocks. Right-click on the software shortcut or executable file. Select .

: The public UDK is a frozen snapshot of Unreal Engine 3. It has its own maximum expected values for PackageVersion and LicenseePackageVersion . When you try to load a UPK, the UDK checks its own MaxExpected version against the file's PackageVersion . If the file's version is higher than what the UDK expects, or if the LicenseePackageVersion doesn't match the expected value, it throws the error and refuses to load the file. The error message explicitly shows the values it found in the file and what it expected, such as:

The "License" portion of the error refers to the validation file that tells the UPK software that your copy is legitimate and has not expired. The system looks for this file in a specific directory.