Can't upload my solution to a weekly challenge?

I am trying to upload my solution for a weekly challenge, but when I attach my workflow file and try to post, I get the following message:

Can someone provide the solution to this issue?

Thanks!

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Community

Accepted answers

We added a fix on community. I just tested it and it seems to be working now. Please try to verify it on your end. Thanks for your patience.

Same here -- I figured it was because I just joined today?

I'm also getting the same! Tried on a number of different browsers and appears to be the same across all.