Yosemite - login screen on low res

I've also tried resetting the PRAM and it has made no difference. This is getting annoying... =(

I have the same issue. I noticed this only happens when using HDMI (both through the direct HDMI port on rMBP or using Mini DisplayPort to HDMI adapter). If I unplug the HDMI cable at the login screen and reconnect, it fixes itself. When I use Mini DisplayPort to VGA this issue doesn't happen.

I've also tried resetting PRAM as well but no luck. This is frustrating! How did this pass through Beta testing? =(

Same issue here as well. MacBook Pro (Retina, 15-inch, Late 2013) with HDMI external monitor.

Yep, same problem for me on a rMBP. Don't have an external monitor plugged in either

I am having the exact same problem on my rMBP.

Same problem as everyone else here. Mine started after I connected my 2012 retina macbook pro to my apple tv using airplay. The login screen has had the same large low res issue ever since and I have had no success on fixing the issue. I suppose there will be an update to fix it eventually. Till then, at least everything else functions as normal, it just looks really ugly.

I read the comments thinking this isn't going to work, but resetting the PRAM worked for me. I did hold down Opt, Cmd, P, R too long though and heard 3 startup chimes. Not sure that makes a difference.

Same here on late 2013 17" MBP, but its also occurring for me post login, and cant access System Preferences because the resolution is so low. I have to log out and back in again and it restores to retina resolution. For me though this only started occurring after I bought an external 4k monitor (connecting via DispayPort), this did not happen under my HD monitor, (also Displayport connected).

Anybody on 10.10.1 yet? Is this bug fixed on the update? Hate the login screen looking like from the late 80's ...

I actually just did a fresh install of 10.10 and installed 10.10.1 on the day of release. I didn't actually have the problem since I did a fresh install. So far I'm not seeing aa return of this issue.

I'll upgrade to 10.10.1 soon and update on the status...

Seems to have finally been resolved with the 10.10.1 upgrade 🙂

You guys are lucky then! I've been on 10.10.1 (From pre-release update seed to full release) and this issue was not fixed for me. At least my WiFi is stable now.

I think I may do a fresh install like northernmunky. Not just to try and fix this issue but bunch of other ones: Airplay mirroring, Spaces, shutdown hangs, etc. Really not enjoying Yosemite right now 😕... never had these issues with Mavericks!

I am sure a fresh install will restore the system - though the issue will still remain.

Just upgraded to 10.10.1 and the issue is gone.