As of today (May 30, 2024) the Items Library and Image Library pages within our Square Sandbox are no longer loading. These have both worked fine for the last 5 months.
On the pages I am receiving the error: “Oh no, something went wrong.
It looks like we are experiencing some problems on our end.” Please see provided image.
Interestingly, the Categories page within the sandbox still loads, and indicates there are Items under the categories, but we cannot edit them.
This appears to be an issue on Square’s end. Is there an ETA for a fix?
Thanks.
What’s your application ID? 
The team has deployed a fix. Thanks for bringing this to our attention.
Great! It’s working now. Thank you immensely.
@Bryan-Square I am seeing the same issue as @gesmith on my sandbox.
I am new here, I have uploaded some fake catalog data and want to attach image data but the the image library does not display at all.
I also created a new sandbox - zero catalog items, and still the image library does not display.
My App ID: sq0idp-zvfPyhP-puSoQbwoWL6duw
I’ve reached out to the team about this but given that sandbox isn’t fully feature complete I’d recommend testing in production with the catalog. 
