Interesting that Lem hated Tarkovsky's first screenplay for Solaris, as did the soviet authorities, so T had to go and write another. 

I have a British Film Institute account for their online streaming thing, and Stalker is critic Mark Kermode's film of the week. Amused to notice that the crew ran out of booze (and other provisions) during filming and resorted to drinking cheap cologne mixed with sugar. Much drunkenness ensued. Tarkovsky sacked his art director on a charge of "behaving like a bastard".

For different reasons, I assume?

I imagine so, although it was probably the same departures from the original that displeased both parties.