Why does Photoshop fail to save GIF but has no problem with same GIF in smaller size?

Question

I need to save an animated GIF in two sizes: 357 by 500 px, and 860 by 1204 px.

The 356 px-wide version saves fine, but the 860 px version comes up with the following error:

Adobe Save For Web Error: Could not complete this operation. An unknown error has occurred.

I tested making it 600 px wide and that saved fine too.

I am using an early 2015 MBP with High Sierra 10.13.3 installed.

I’ve tried deleting the various save for web preference files, and tried both CC 2018 and CS6. The same thing always happens. How do I fix this?

Solution

The file you trying to export is probably too large.

Try reducing the number of frames before exporting.