Photoshop has a 2GB limit for PSD file sizes, and I only discovered this after using Photoshop for 10 years. The problem is the error message is exceedingly unhelpful.
Could not save [filename] because the document is bigger than 2 gigabytes.
See help topic 'Saving Files' for more information.
The problem: this description makes it sound like Photoshop has a file limitation of 2GB. It doesn't say "this file format". Just that the document is bigger than 2GB and thus it can not be saved. Further, the description does not provide a solution. It tells me it can't save, then suggests I go search for it.
Fair enough. I went to Adobe's help (looking up Photoshop only) and searched for "Saving Files". NONE of the results on the first or second page applied to my problem. When you want to save a file and can't it creates a bit of anxiety. The only solution/suggestion it provides does not contain the answer.
The error message should be able to determine if a user is attempting to save in PSD and offer a message which states something like:
Could not save [filename] because the document exceeds PSD file format's 2GB limit. Please save using Photoshop's Large Document Format (PSB).
This instantly gives users a solution without having to search, and explains PSD files has a limit of 2GB, not Photoshop itself.