I'm trying to upload an image but rule34 won't let me and tells me: "An error occured. The image could not be added because it already exists or it is corrupted." & "Some code seems to be injected into the image. Don't try uploading it again. Resave it as a lossless PNG and upload it again."
I don't know how I am to convert my gif to png. I've tried some things but they turn out horrible.

P.S. I don't own photoshop

lmgtfy.com/?q=gif+to+apng

OOoooh I didn't know apng was a thing. Thanks

:( no matter which program/website I use I keep getting a still image not an apng.

Some browsers aren't compatible with the APNG format and will show it as a still image.
en.wikipedia.org/wiki/APNG#Support

I love you

You don't really have to convert it to apng to make it uploadable here.

What I do when I get that message is resizing the gif (reducing by just one pixel the height or width would be enough). You can use an online converter like this one: cloudconvert.com/gif-to-gif

Eh whatever. I converted the image to apng then converted it back to gif. Everything looks fine