I have been trying to clear all dropped items on my server I am running, as one of my players dropped too many items from a sieve and now whenever he logs on it crashes the server. How can I clear all the items.

After a bit of tinkering, found the solution:
/kill @e[type=realdrops:item_loot]

yeah for some reason /kill @e[type=item] doesn't work for me. but you can try it.

I think I'm just going to roll back all the changes I made to the last few builds to fix mods double checking their drops weren't deleted/replaced. There are so many other issues people are having with it and I'm frankly getting tired of it.

Note: This won't fix the kill command because the entity has a completely different ID realdrops:item_loot