Has there been some significant change in the aTTiny core configuration? It's been a couple of months since I last uploaded to my Tiny85 chips, but it fails today, with the familiar series of sync messages.
I'm using the same setup, wiring and procedure: Arduino UNO with Arduino as ISP. The target chip is still correctly running the last sketch I left it with. Tried several other chips too. My suspicion is that this URL in the Additional Boards Manager list may have changed?
