This bug was reported in this channel 2 months ago on 6.3.1, but It's now happening to be on 6.3.4 and I'm not sure how to fix it. A single player is getting kicked with fatal errors when they rare candy pokemon. Trading the pokemon fixes the issue, and I can force evolve. This is the error that spams console: https://pastebin.com/SHyMMTmd

Additionally, after their pokemon is finally evolved, by force or by trading, the player can no longer battle any pokemon. When they initiate battle they are flashed with the level up message, and then kicked out of battle. Relogging does not fix this, and no error spits into console when this part happens.

I made sure the player in question only had forge2705 and pixelmon6.3.4 installed as well. The only reason I am creating another report is to possibly provide more information as it would seem the previous bug reports didn't provide enough to fix the issue. Unfortunately I am unable to accurately reproduce the error on myself or other players, which led me to believe it was the player themselves. I ended up mimicking their mods, versions, and launcher in an attempt to recreate to no avail. Other players have reported this, but I've only confirmed this case. I also tested inside and outside claims of different types, but the issue persists.

Forwarded, keep an eye on the ticket status to know when it is fixed. Thanks for reporting! If you have any more information, please update the ticket :)