OK
2. Updating NodeBB data store schema.
5/3 11:01 [2536] - info: Beginning database schema update
5/3 11:01 [2536] - info: [2015/09/30] Converting default Gravatar image to default User Avatar skipped
5/3 11:01 [2536] - info: [2015/11/06] Gravatar removal skipped
5/3 11:01 [2536] - info: [2015/12/15] Upgrading chats
5/3 11:01 [2536] - info: [2015/12/15] Chats upgrade done!
5/3 11:01 [2536] - info: [2015/12/23] Upgrading chat room hashes
5/3 11:01 [2536] - info: [2015/12/23] Chats room hashes upgrade done!
5/3 11:01 [2536] - info: [2015/12/23] Adding theme to active plugins sorted set
5/3 11:01 [2536] - info: [2015/12/23] Adding theme to active plugins sorted set done!
5/3 11:01 [2536] - info: [2016/01/14] Creating user best post sorted sets
5/3 11:01 [2536] - info: processing pid: 5 uid: 2 votes: 2
5/3 11:01 [2536] - info: processing pid: 7 uid: 4 votes: 1
5/3 11:01 [2536] - info: processing pid: 17 uid: 2 votes: 1
5/3 11:01 [2536] - info: [2016/01/14] Creating user best post sorted sets done!
5/3 11:01 [2536] - info: [2016/01/20] Creating users:notvalidated
5/3 11:01 [2536] - info: processing uid: 1 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 2 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 3 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 4 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 5 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 6 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 7 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 8 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 9 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 10 email:confirmed: null
5/3 11:01 [2536] - info: processing uid: 11 email:confirmed: null
5/3 11:01 [2536] - info: [2016/01/20] Creating users:notvalidated done!
5/3 11:01 [2536] - info: [2016/01/23] Creating Global moderators group
It stops here. I try several times, but it never moves forward.
Thanks for reporting, it should be fixed on master and 1.x.x.
https://github.com/NodeBB/NodeBB/commit/7180174b91895c907991e29238ecb5822d5d7cb6
https://github.com/NodeBB/NodeBB/commit/8f8fcc84168d424c7bdbf16ad4afae2cca36991c
Safe to upgrade now?
@Jenkler You should always backup your data first. When a version is released it's always expected to be "safe to upgrade", it just doesn't work out each time. But without someone who tries to upgrade the devs won't find each edge case that may fail 
I wanted to know if there was any known breaks at the moment 
Backup is always needed! I will update my devs first.
