Meteor 0.8.0 is out with the new Blaze rendering, which is great... for the future.
At the present I can\'t run my Iron Router powered app: updated -> ran meteor ->
You have to update your iron-router package. Check out the Iron Router github page https://github.com/EventedMind/iron-router for information on what's new in their 0.7.0 release. It works for Meteor 0.8.0.
Just faced the same issue,
Did the following and works fine
It occurs mostly because of the iron-router package and few other packages which are using spark
as dependency and first re-install the iron-router like below
meteor remove iron-router
rm -rf packages/iron-router
mrt update
mrt add iron-router
Just re-installing the iron-router will update you to the new version and also it installs blaze-Layout
automatically with the iron-router(which is the new templating system).
After updating iron-router,Even now if you are getting spark
is not defined error,check which package is using spark
and update those packages too.