27" 5K Retina Display iMac (Late 2015) Screen glitching and crashing with no replicatable cause.

Error 5101...

So, according to the articles, I have an incompatible Boot ROM version (or commonly known as BIOS). (To check it, go to the Apple logo - About My Mac- System Report - Hardware and see the number of Boot ROM version)

And that was right! I have two other MBPs and the Boot ROM versions were 428 for the 2014 and 424 for the 2015. The problem one was still at 192. My speculation is macOS has something similar to a compatibility mode so it could run on older BIOS versions but couldn’t boot from the Recovery Partition, especially Big Sur. I bought this Mac with no SSD and put in an SSD with Catalina pre installed, so the BIOS was probably not updated.

So how I solved this was pretty time consuming, but it worked! I used Shift Cmd Opt R to get Yosemite back on the SSD. Then I went to App Store and updated to Big Sur. After a longer than usual update and many more restarts that took about 3 hours total, my Boot ROM version was updated to 424 and the problem was solved.

EDIT: I got another one with ver. 180 firmware and when I trigger IR it doesn’t error out anymore, but the latest OS it could go up by IR is Catalina. From there I could manually update to Big Sur 11.1 but the firmware version stays the same. And of course, no access to Recovery partition. They fixed it in a half-assed way.

https://www.reddit.com/r/macbookrepair/comments/kab0an/error_5101f_on_macbook_pro_2015_and_how_i_solved/

5101F error - Apple Community

Try this, I was also getting the same 5101F error..

pressing Option+Command+R doesn’t work so I reinstalled the earlier OS by pressing Shift+Option+Command+R and then Start button.

 It takes nearly 30-40 minutes to reinstall the earlier version of Mac OS. In my case I had Catalina installed by earlier version of Sierra installed.

 This will definitely work..

5101F error - Apple Community

I see a couple of things, the computer is definitely suffering from Kernel Panics which may be caused by either hardware or software. I don't see any of the normal software indications so that leads me to believe the KP's are caused by hardware.

The most common hardware causes are RAM related and failing hard drives. I see your computer has 16GB of RAM, was the computer purchased with 16GB or was it upgraded? Also, what brand of RAM was purchased (assuming you upgraded it yourself) and where was it purchased from.

The second thing to check is the internal HD, it's almost 10 years old and is WELL past its prime! I recommend that you download DriveDX and test the internal HD. If ANY errors appear on the DriveDX report then that pinpoints that you have a failing HD that should be addressed.

Considering the computer is so old, if it is the HD I would not recommend spending any money on it as the computer is obsolete and has little monetary value. I would seriously consider replacing it with a current Mac mini and add a display of your choice. You can do this for <$1200 and get a MUCH MUCH faster and more stable machine than your 2015 27" iMac.

I don't know if anyone has found a solution but one thing I have found that works is "not" using a wireless keyboard and mouse. Whenever I do, it causes the screen to glitch after a certain amount of use. When I tried using wired keyboard and mouse, the problem went away.

Hi,

Try to check your iMac with Apple Diagnostics if your iMac issue could be caused by hardware related issue.

Use Apple Diagnostics to test your Mac - Apple Support

Thanks, please do the following:

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again. 

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community It is helpful to us if you download the report to your Desktop.

We need to see what all is running, a report from this will not display any personal info...

Using EtreCheck - Apple Community

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Thanks for Old Toad’s etrecheck instructions…

Slow iMac 2017 - Apple Community

Use the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

Well the only thing left I can think of is Mac OS may have become corrupted or damaged somehow.

• Please backup the computer next.
• Restart the computer into the Recovery Partition
• Install Mac OS, this will not affect your data or apps. What it will do is fill in any damaged or missing parts of Mac OS.
• Restart the computer normally and test.

Do you have any of the following third party apps installed on your Mac?

·      Antivirus Apps

·      Cleaning Apps

·      Security Apps

·      VPN Apps

·      Maintenance Apps

Have you ever done an erase and install on this computer or restarted into the Recovery Partition at any point?

You need to erase the drive, the whole drive, as above...

Have you tried installing to an external drive?

Come to think of it, not sure if s 2015 iMac wants APFS or HFS+ for HS.

In Disk Utility>View, select Show all Devices, highlight the top left entry.

APFS won't work for Sierra or earlier, Sierra or earlier needs MacOS Extended Journaled. High Sierra won't work for APFS on earlier Macs.