I'm having a weird issue in PS 2018 with droplets - almost as soon as I try to use the droplet on more than 6 or 7 files, it gives me an error message that states, "Could not complete your request because there is not enough memory (RAM)." It does not completely stop - it will continue to process the remaining files, but anywhere from the 3rd to 6th image does not process, so I have to go back and hunt to find which one did not. It's always only one file. The size of the files do not seem to affect whether the issue will occur - it will do it with 330K JPGs the same as 20M tiffs. I'm working off a new Mac Pro laptop with 16G of RAM. I did not have this issue in previous version of PS.
I have the same issue on the latest Photoshop (23.5.0) on a MacBook Pro late-2019 with 16 GB RAM.
I did not realize it was a memory complaint because it only gave a cryptic "An error occurred" in Photoshop on the one (and it is always just one) that fails. I found that as soon as I saw that an image file was skipped in the Finder if I looked at the error log that I defined in the Droplet creation dialog, I could see an error message like this:
Error: Could not complete your request because there is not enough memory (RAM). (-108)
The files in question are only a couple megabytes and it is routinely one of the first dozen or fewer files that is skipped. There is always one file skipped on a Droplet job.
This is a problem that I have been having for years and finding frustrating. It helps to define an error log so it won't stop at the first error. It will run through the full list of files dropped on the Droplet icon. Then Photoshop will open and complain of the vague error. Close the gray window for the file. Drop the one file onto the Droplet icon and it always works on the second time.
This error has not been resolved in the past 4-5 years and the hidden error messages probably prevent others from figuring out what the cause is and some way to fix it.
I have seen some references to Windows Registry edits but that exact solution won't work on a Mac. In a pre-2000 MacOS one could assign RAM levels per application. But I don't think it is a real out of memory condition because I have menu bar monitors to show the status of RAM, etc. and it is normal.