The new iron:router 1.0 requires this.next() 

after onRun(), onBeforeAction() etc. 
See details here: https://github.com/EventedMind/iron-router

The problem was that suddenly the page turned blank and the console reporting: 
"Route dispatch never rendered. Did you forget to call this.next() in an onBeforeAction?" 

After elimination all my own onBeforeAction, onRun etc. I went through the packages that I use and found the problem in herald. Hopefully someone will save the half day that I spend on the problem.

Se https://github.com/Meteor-Reaction/Herald/issues/24