Unity Unable to Launch the Editor - Update

In the last few days, a large number of Unity users were unable to launch the editor after choosing their project. Many users discovered disconnecting from the network or retrying would get them through to the editor, but it’s obviously a frustrating issue we needed to remedy.

So, after digging in, here’s what we uncovered...

Problems always happen in clusters
First, one license server out of a set was acting up, so when a user’s timing to check the license came up, it had a random chance of connecting to an ineffective server. Having solved this, we were slow to realize there was a second problem at hand.

The second problem stemmed from a TechOps DNS configuration change moving some file serving from one location to another that had a far more subtle impact.

In our editor project open process, we check for a file on update.unity3d.com for possible updates. This in turn, re-directed to another location (the one moved). This second change uncovered a third problem: a editor web request implementation flaw and timing issue (being now corrected) that result in us to indefinitely wait on the re-directed fetch since the server responded with a different SSL/TLS configuration, thus stalling the whole project open process.

Solution
So, for those impacted, we have changed back our TechOps configuration, but this is a DNS change that requires time to propagate. Ideally, you restart your Editor and everything should now work.

If not, the known workarounds are:

• Disconnect your network when opening your project
• Use the lmhost or hosts file to locally re-direct update.unity3d.com and cdn2.unity3d.com to 0.0.0.0 or somewhere that won’t answer with the SSL/TLS we didn’t handle correctly (eventually, we’d recommend removing the line as our re-direct back to the original service will have propagated).

In the long run, we’ll also fix up the web request pathway in the Editor to handle this condition correctly, but that won’t solve it for the existing releases out there. We’ll maintain our service configurations as-is until further notice.