Hello, i’ve been trying to install the 2.5.1 release as mentioned in the releases page Releases - Ember.js, but it seems there is no ember tagged with 2.5.1 there is only 2.5.0 tag or 2.6.0 prereleas.
The releases page you referenced is incorrect, there is no 2.5.1 version yet. Just go with 2.5.0.
There was a mistake during the manual updating process, we’re fixing it shortly 
Thanks for bringing it to our attention.
OK, just redeployed the site, sorry about that!