@MachineX
This is due to the mods if I recall correctly. What I did was downloaded the 4.18 copy of the source. Opened it in 4.18. Then if you upgrade it, it should tell you that the rifle mode and the other mod are not supported would you like to disable them.
Say yes.
Then find all the mod references and remove them or work on trying to upgrade them to 4.19. I’m going to revisit modding later but this got me started.