Thanks for the feedback @dr_st, I will fix the gun locker door – that’s a good catch!
I tested with PrBoom+ 2.5.1.4 and do not get that error. That is strange indeed, considering I did not change the SKY textures.
Are you loading any other WADS, like custom sky boxes or perhaps a mod?
SKY4 is a texture introduced in the Ultimate Doom for the fourth episode.
If your DOOM.WAD file is not the Ultimate edition it will be missing SKY4. Can you try run PrBoom with the “-complevel 2” option? This will force the engine to run in Doom 1.9 compatibility.
If you know for a fact your WAD is from Ultimate Doom, then ignore all of what I said, and I can’t think of what else might cause this, I will do some research …
