Yosemite takes around ~30 minutes to boot.

[Intelligent]

Anyone else that has this problem? The progress bar gets stuck in the middle and nothing happens for like 30 minutes then the screen just turns black. Yes, i know its a developer preview, but i have been able to boot before and if it is a preview i should at least be able to boot it up. right?

 

[merrickdrfc]

Try a fresh install, then restore your data. If you updated it can cause pretty weird issues, this looks like one of them. A fresh install usually fixes 90% of weird glitches that aren't documented

 

[Shmanky]

Try booting in verbose mode to see if it's one particular thing that's causing the delay during boot. Hold Command-v during boot to see the white text.

 

[Yakibomb]

Try a fresh install, then restore your data. If you updated it can cause pretty weird issues, this looks like one of them. A fresh install usually fixes 90% of weird glitches that aren't documented

Just for interests sake, why does updating cause all these weird problems?

 

[jonbravo77]

Just for interests sake, why does updating cause all these weird problems?

Updating is sometimes like putting a band-aid on a severed leg. May feel like it's doing something helpful but it really isn't. Doing a fresh install will get rid of problematic files that may be lurking about.

 

[Hackintosh Sr.]

Had same issue last night. I just held down power till it shut back off while it was stuck. Hit power again and everything booted normal.

I have a fresh install of 10.10 beta 1 and then have upgraded to beta 3. I will try verbose next time. Thanks for the suggestion

 

[mavis]

I'm having the same problem. Installed over Mavericks on a 2012 iMac and when it booted up, I couldn't see the taskbar or dock. After rebooting into safe mode (well, trying to, anyway) it's frozen as the OP described.

This is just great.

 

[thirdeyeopen666]

Run SMART Utility to make sure your hard drive isn't failing. If it passes, run a disk verify/repair.

 

[mavis]

I did a verbose boot; it seemed to be hanging on rebuilding kernelcache or some such - anyway once it got through that it all went back to normal. YMMV