Cause

At least one property of the data for a protected main function / main terminal that you have placed as a part with defined function templates (device) has been changed retrospectively (e.g. the Technical characteristics property). This type of change to a protected main function / main terminal in parts data that have already been selected is not permitted.

Solution

1. Note the property that was output in the message.
2. Use the Go to functionalities to locate the main function / main terminal in the project.
3. Open the properties for the protected main function / main terminal and compare the data for the property specified with the data for the corresponding property for the selected part.
4. If the data are different, undo the retrospective change to the protected main function / main terminal, or select a different part that has suitable parts data.
5. Then start a new check run.