Constantly getting a "Metadata request overflow" error at one torrent.

The "Bytes In" and "Bytes out" are constantly growing (several megabytes already when I write this) yet the meta-info not arrived, so the downloading not starting.

What is this error? How to fix it?

what version and OS are you running?
how big is the torrent going to be?
are you getting this error with the torrent or with a peer?
does the torrent stop?
what happens when you restart the torrent? force check and then restart?
you should post the magnet link or a link to the torrent here so the mod can send it to the dev.

I had this same issue a few days ago. For my issue, magnet link only, turned out the download was Private. In Tixati (when you have metadata) this is indicated by a padlock symbol.

SEE: 2nd item under the NAME header
https://support.tixati.com/transfers%20view

If the creator of the torrent selects private mode, Tixati won't exchange MetaData with anyone else or use DHT.

When Tixati only has a hash there is no way of telling if its private or not, so you may see the IP  peers trying to exchange metadata but fail or overflow.

You'd need to get hold of the .torrent file probably by this stage of trying?

If you have the .torrent and it still can't find peers (it wont use DHT) you need to add a tracker, or as many trackers as you can, to see if any peers will share.
Maybe work out where the download came from and use trackers associated with them.

If you know its not a private torrent, try copying the magnet link to text file, delete the transfer from Tixati and re-add in case of glitch?

If you see multiple active, normal peers from various networks, not just a single peer, it might be a bug. Post the magnet or the download page link if it's public for developer to check.

If it's a single peer, or a couple seemingly linked ones, it might be broken on that side, or it might be a deliberate sabotage. I hope you know how to spot legit and fake torrent sites, and haven't run any “helper app”.