I have both Mist and Geth installed. One note though; Mist uses (is bundled with?) Geth 1.6.0 whereas I have Geth 1.6.1 installed.
When I type
> geth --testnet --fast console, I fail to sync the testnet. After some block, I start to get only messages like this (copied from here):
WARN [04-21|17:40:40] Ancestor below allowance peer=20c9ad97c081d633 number=647267 hash=000000…000000 allowance=647267 WARN [04-21|17:40:40] Synchronisation failed, dropping peer peer=20c9ad97c081d633 err="retrieved ancestor is invalid"
However, when I close this terminal (remove chain data) and start Mist and click "Use the test network", it syncs with Ropsten correctly. Is Mist passing other flags that I need to use too? Or is it just a problem with Geth 1.6.1?