Hi Soulskeeper,
I believe your issue lies with the fact that you are attempting to use a tessellated material with particle sprites. That isn’t possible, if you want to use tessellation change your particle type data to “mesh data” and recompile the material. If your material is assigned to any particle sprite it will be flagged as being used with them and return the errors you mentioned earlier.
Even though you had tessellation enabled in earlier versions it shouldn’t have been doing anything with particles other than type mesh data particles so it is probably for the best that this error came up. In general I would recommend not using a tessellated material with particle systems since this can be pretty expensive depending on what you are doing.
I hope that helps!