I'm not sure of what you mean by "You need to cross check your disk space".
I have the source code for 3.90 and I am not sure of why this is happening. The path C:\Users\Tony\Documents\Visual Studio 2017\Projects\Lakeside390\Libraries\Nop.Services\Media\ is on my local disk. I don't understand how it is getting that when it is running on my service provider's system.
Any additional help that you can provide to figure this out would be gratefully appreciated.
Don't know exactly what is issue, as per your error log it says disk space full and it's preventing to create new logo.
Do one more thing, check folder permission write permission,If permission issue than it give GU+ error. it's not issue but just be sure from permission.
There are over 70,000 files in those folders that were put there by me importing products with images through Excel.
I never had one There is not enough space on the disk log error while I was doing that. Why would it all of a sudden start doing this in the past two weeks?
If "service provider and they say that we have over 1GB of disk space available", then no it may not permanently fix the problem, but it's something to try.