Hi @andersonbrito! Very interesting to see this error popping up again. This is a rare error that sometimes happens with TreeTime during the refine step. It’s usually a one-off and restarting that step clears it - but clearly that’s still irritating if it’s been running for a while! Can I ask, what version of Treetime are you running? We had hoped that the latest updates had cleared this error. I’ll tag in @rneher as well, as he’s been the one tracking down the error!