When you throw an item through a nether portal in the overworld and the chunks, where the opposite portal stands, aren't loaded, the server will crash.
We tested it twice, when somebody was in the nether - the server didnt crash ; when nobody was in the nether - the server crashed when we threw an item through the portal.
Thank you for your report.
However, your ticket has been resolved as a duplicate.
This issue has been linked to the original bugreport: MC-73866. You can find or add further information on that report.
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