The production version of ImageShare is currently unable to upload images to Imgur, because the API returns this error:
string(109) "{"data":{"error":"Imgur is temporarily over capacity. Please try again later."},"success":false,"status":403}"
My local setup with the same Docker container and same API key still works, so I assume this is a (hopefully unintentional) IP block. I've updated the upload code to use binary files instead of base64-encoded images, and tried moving the server to a different DigitalOcean region, but nothing changed there. I also rolled out basic error handling, so ImageShare won't silently fail when an upload fails (which was generating a QR code that linked to the Imgur home page).
I'll update this thread as I investigate other solutions.