This doesn't sound like the sort of size errors I run into, but there are definitely image size limits (not quite sure if its dimensions or sheer file size) in Lemmy - have you tested with some small images?
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Works for me.
LW may still limit some actions if you're on a VPN. If you are on a VPN, try with a direct connection.
~~I am not well versed with VPNs. But I am on my mom's wifi and she has a VPN on. Does that effect this? My phone has no VPN installed but my mom's PC has one on. Do VPNs effect all devices connected to the same wifi?~~
Nevermind. I tried uploading it with only a data connection and it still gave error. The problem isn't the VPN. My mom doesn't know if her VPN is installed on her PC or the router she has but it has to be a server side error.
A 500 error is generally a server side error. If you have tried multiple images and aren't using some oddball format (use the Linux "file" command to validate the image format). Then I'd reach out to the server admin.