Unmerges edges when moving.

[k.moonsXH6PH]

I made a model but after rigging it, it "opens up" when I move the upper joint. I still think that this is for the modelling forum but maybe I'm wrong. I merged the edges a few times but I don't know what to do anymore. 

https://imgur.com/a/AZYNQIh

https://imgur.com/a/eM3yzYE

https://imgur.com/a/X4cHRza

[mspeer]

Hi!

You have history(edited the object) after skinning.

You need to delete this part of the history and you may need to re-skin.

[_sebastian_f · Accepted solution]

you did a lot of modeling operations after you bind the geometry to the skeleton. that should be avoided as much as possible. in your case edit > delete by type > non deformer history should work.
if not: unbind the geo. make sure your mesh is finished and delete history before skinning it again.