Set a maximum rollback height

src/rpc/blockchain.cpp

@@ -1212,7 +1212,7 @@ UniValue invalidateblock(const JSONRPCRequest& request)
     if (request.fHelp || request.params.size() != 1)
         throw std::runtime_error(
             "invalidateblock \"blockhash\"\n"
-            "\nPermanently marks a block as invalid, as if it violated a consensus rule.\n"
+            "\nPermanently marks a block as invalid, as if it violated a consensus rule. Note: Your oldest sapling note must not be more than 43200 blocks behind the chain tip\n"
 
             "\nArguments:\n"
             "1. blockhash   (string, required) the hash of the block to mark as invalid\n"
@@ -1234,7 +1234,7 @@ UniValue invalidateblock(const JSONRPCRequest& request)
             //Do we need to recreate the witnesscache or is the current one enough?
             if (pwallet->GetSaplingScriptPubKeyMan()->nWitnessCacheSize <= (chainActive.Height() - pblockindex->nHeight + 1)) {
                 if (!pwallet->GetSaplingScriptPubKeyMan()->BuildWitnessChain(pblockindex)) {
-                    throw JSONRPCError(RPC_DATABASE_ERROR, "Cannot load default note values");
+                    throw JSONRPCError(RPC_DATABASE_ERROR, "Sapling notes are too old!");
                 }
             }
         }