Hey, So yes this is a known issue, I thought we had a fix in 5.4 but apparently i was mistaken. I’ll try and track it down see if it just got missed for 5.4 or if we truly hadn’t fixed it.
I took a look into the bug and managed to solve it.
When running into this bug, try to reimport the Plugins folder by right-clicking on it and choose ‘Reimport’. This might regenerate some files which are causing the problem.
If this doesn’t solve the problem, do the following steps:
In your project navigate to the Plugins folder
Look for a file named ‘Photon3Unity3D.dll.mdb’ (the filename extension is very important) and delete the file if it exists
Within the Plugins folder navigate to each PUN-related subfolder (Metro, Uwp) and
Look for ‘Photon3Unity3D.dll.mdb’ again and delete the file if it exists
Just to summarize, we actually do have a bug still open - it’s related to duplicate asset names existing oddly enough. So like @ChristianSimon found, deleting duplicates of the same named files will do the trick.
Working on fixing it still, but it’s a bit trickier to work out and no timeline set for the moment.