An error occured while preparing your download. What do I do?

I publish model a long time ago, but not check after uploading.
Now I see this bug
An error occured while preparing your download.

Your model won’t appear as downloadable.

We have been notified and will fix it as soon as possible.

How long it may be and how I can fix it& It can’t be changed, I try.

You could try disabling the download, then re-enabling it to see if it gets correctly processed.

If that doesn’t work, your best bet is open a support ticket here: https://help.sketchfab.com/hc/en-us/requests/new