pls provide some version info and other useful information such as the log files.

i cannot reproduce this with the newest 1.15 version

Yep, fairly common problem for the newest version for 1.15.2, simply turn into a bat while viewing yourself (3rd person) or view another player as a bat and immediately be ejected out of your world.

Without a crash report there is nothing we can do since we cannot reproduce it.

crash-2020-05-08_19.59.01-client.txt

Thank you.
Unfortunately, the game crashes at a position where the crash log does not give sufficient information alone.
I still cannot reproduce it with the exact versions of Vampirism and Forge, so I assume there is some kind of mod conflict.
Could you export your MultiMC instance and drop it here:
https://cloud.maxgb.de/s/gt5EbF9bfWAG9ie
(I only need the config and mods folder as well as the saves folder if you can reproduce it in SP)
Thank you

This issue has been automatically closed because there has been no response to our request for more information from the original author. With only the information that is currently in the issue, we don't have enough information to take action. Please reach out if you have or find the answers we need so that we can investigate further.

Bad bot!

If we can get a modpack, where this crash occurs we can try to narrow down the conflicting mod. Otherwise there isn't much we can do, unfortunately

This issue has been automatically closed because there has been no response to our request for more information from the original author. With only the information that is currently in the issue, we don't have enough information to take action. Please reach out if you have or find the answers we need so that we can investigate further.

ok here's the instance export from MultiMC
https://file.io/RW5jVq0U

Well, that's just the worst file hosting service ever, no matter. I put it on my dropbox now https://www.dropbox.com/s/6tij1k7xyx9z8px/%5B1.15.2%5D%20Modpack%20Omega.zip?dl=0

Thank You.
I have narrowed it down to upgrade aquatic.
The crash is caused by a bug/design issue in that mod. I will create a issue over there.
Unfortunately, there isn't much I can do on our end :/

Should be fixed with the latest version of Upgrade Aquatic. Let me know if not