Unable to select new scratch disk location photoshop 2018

[louisaw91393746]

hi,

I'm having problems doing more than 3 minutes work in photoshop 2018 without it telling me my scratch disk is full, despite the fact I have cleared my MacBook over and over to free up space. I've tried to change the scratch disk to my external hard drive by going to preferences> Scratch disks etc but my External HD isn't showing as an option and it won't allow me to de-select the Mac HD option either. I have also tried launching PS and pressing Command option and doing it that way, but that doesn't show my external HD as an option either.

Any ideas? It won't even allow me to save my work so far because the scratch disk is full.

Any advice would be greatly appreciated! Thanks!

[JJMack]

I use windows but see if the this works for you. Close down Photoshop.  The start Photoshop and immediately press and hold theCMD+Option keys. You should get a popup dialog the looks something like this and be able to change your scratch disk configuration.

[Test Screen Name]

It isn't clear whether you are saying the message can't be right. Just how much space IS free on your C drive?

[Test Screen Name]

Sorry, how much space is free on your Mac's internal disk?

[louisaw91393746]

There’s about 11Gb left on my MacBook internal hard-drive.

[Test Screen Name]

Not enough. You need to free a lot more space just to keep your system running smoothly, still less run Photoshop. You can add an external disk so long as it’s formatted correctly.

[louisaw91393746]

That’s the problem, I’ve tried to add my external HD but it doesn’t come up on the list of options no matter what method I try. From what I’ve researched, it is formatted correctly and it is writable.

[Test Screen Name]

Sounds good, but how is it formatted? If you aren't sure what format it has and don't know how to find out, please let us know.