I have updated from v0.18 to v0.21.2, it broke my indexer, so I had to add the -rpcserialversion=1 flag, which (as I understand) disables the MWEB fields to prevent this.
I wonder if I could have issues somehow to know the right balance for addresses.
If u did the update after the mweb activation u need to resync the full blockchain data.
And welcome to litecointalk 
I have also updated my wallet version from 18 to 21 but after updating I am not able to mine solo on version 21… Solo mining working fine with version 18…
In version 21 it always gives error… 500 internal server, json rpc failed…
Do you know what to do to solve this issue…