Project not loadable for unknown reason (unsupported fixture type) ENS-12292

In very rare cases it can happen that previously working project files are not loadable on the PC / Core S anymore.
A reason for this can be a broken fixture library.
When you try to load *.hfp files which worked previously and now you are facing  error messages like this

ERROR 2024-02-19 16:07:47,015 [27] Sympholight - Unsupported device type (Manufacturer: Generic, Name: RGBWFader)
ERROR 2024-02-19 16:07:47,099 [27] Sympholight - Unable to load data from the project file. Failed region: Topology
ERROR 2024-02-19 16:07:47,336 [27] Sympholight - There was a problem loading the project file /mnt/data/SYMPHOLIGHT 5.3/CurrentShow/Captain Cook Square V1.15.lprj: The file content is invalid or incomplete.

then it could be that the "ImportedFixtureLibrary.xml" is broken.
Deleting the broken "ImportedFixtureLibrary.xml" should fix the issue with loading project files.

Core S:
On the SD Card it can be found in the folder "\data\<SYMPHOLIGHT 5.x>\"
where <Sympholight 5.x> has to be replaced by the current used version

In the example below it is  SYMPHOLIGHT 5.3:


PC:
In the file system you will find the "ImportedFixtureLibrary.xml" at %appdata%\..\local\ecue\<SYMPHOLIGHT 5.x>
where <SYMPHOLIGHT 5.x> has to be replaced by the current used version

In the example below it is  SYMPHOLIGHT 5.4:


Currently there is just one known case for PC and Core S where this happened and it is unknown what leads to this situation.