In 2015 I wrote this post, describing how to fix external monitor blurry fonts that occur when upgrading OS X to Yosemite or El Capitan. Here it is almost two years later, and when I upgraded to macOS Sierra, the same phenomena occurred again.



Update 24 January 2018: The same exact process works for upgrade to High Sierra.

I experienced blurry fonts on a Mac Mini, but the same fuzzy display issue is also reported on MacBook Pro external monitors. The steps to fix this issue are largely the same, but today there is a more succinct explanation of the steps required to restore your display back to normal.

I'll guide you on what to follow in this post, so if you've landed here from doing a search, you won't have to continue searching and trying solutions that do not work.

Go to this post and follow steps 1-9 as they are stated in the section How to force RGB in Mac OS X. This references one other post that describes how to disable SIP, and then enable it again once your issue is corrected.

There are two glitches I have encountered each time I have had to perform this process after an OS X upgrade.

When disabling SIP as part of Step 2 (using the referenced post in that step), you may find that there is no Utilities menu item visible. If so, it is there but higher than what your monitor is showing you. If that is the case, click at the top to see the dropdown menus and find the Utilities menu item. You may have to click around a bit to see the right dropdown.

After you restart in Step 7, your monitor may be cutting off the side and top menus. If so, power down the monitor and power back up again.

I'm surprised this is still a necessary process, but at least there is a fairly easy and quick solution!

I encountered one other odd scenario with macOS Sierra. When doing a shutdown or restart, the screen would go blank and just sit there. You could tell that it did not shutdown properly. Some research pointed to the version of MySQL causing the issue. I saw multiple suggestions to upgrade to the latest. I did that, and the installation of MySQL stalled indefinitely. I then came across t﻿﻿his excellent post, which described exactly what I was seeing. I followed the resolution process, which was to completely remove all traces of MySQL, and then install the v5.6 community version. That did the trick and now everything is running smoothly.