Missing Microblocks and Switching Versions

[Spring_Faun]

I tried joining a multiplayer server, although when I did was disconnected and I got an error message that said "The following microblocks are not installed on this client: tile.iron"

Is there any way that I can add this missing microblock?

If not, could anyone tell me how to switch back to 1.0.5? I have no idea to change my game versions, and I'd like to see if it would help fix the problem.

[Rhodiaxx]

To change version, click the gear in the launcher. Then choose "manually select version" and then the desired version. If it asks to update, type YES
It doesnt work for me either for private servers / friends' servers but on larger servers they mastered it.
I hope this helped and greetings
Rhodiaxx