So I have a file that was originally drawn on Paint Tool SAI. This is because I can't draw effective, smooth lines on Photoshop. However, a majority of the file users use programs that can read PSDs... Except we hit a snag.
Every time that any Photoshop users attempt to open the file, we get this error. All other programs can open it fine.
The file itself is 3500 x 2500, 71 Resolution.
2017:04:03 00:31:41 : ..\..\sources\UMerge.cpp : 6495 : REQUIRE failed
Have you tried updating the Photoshop to its latest update? if not, please update it to CC 2017.1.1 version also, you may try and reset the Photoshop preferences and check if that helps.
Refer: Preferences in Photoshop
Let us know if that helps.