Buzzfeed:

Wooooops. A large portion — maybe a majority — of apps that let people post things to Tumblr have been shut out of the blogging service. It seems to be the result of a miscommunication, but it’s likely going to be broken for weeks.

Folks, Tumblr recently turned off access to version 1 of their API with no warning, and as a result users cannot log in to Tumblr using Tumbleroo. We are very sorry and and we are working to update the app. This has happened to lots of other apps as well and we hope to fix things quickly.