Help Me Save My 2013 27" iMac - Kernel Panics (Watchdog Timeout)

I am not a level 10 but I am going to give it a shot

Do you have any external devices coupled to your iMac? External harddrives, external monitors, etcetera? You might want to uncouple those and see if the kernel panics will remain

The kernel panics will not inmeatdetely damage your SSD but it is not good for your computer either, so it is better to solve it.

Also: are you using virtual box or vm ware or parralels desktop on the Mac? You might want to shut down these programs and see if the issue persist, as it can be caused by a memory leak.

Do you have antivirus or so called cleaning programs on your Mac? These do your Mac more harm then good, delete them to see if the issues persist

Also: in system preferences, uncheck Power Nap to make sure if the issue is not caused by a Power Nap setting

I hope one of these things work for you!

KP reports really tell us nothing. You should take the computer back to the Apple Authorized Service Provider that did the upgrade and take up the issue with them. However I would also recommend that you do the following and perhaps we can see what is causing the KP. I say "may" because KPs can be caused by either hardware or software which can make them difficult to determine what the cause is. Very common hardware causes are failing HD's which you have addressed already and can also be RAM related. iMacs (all Intel machines) are very sensitive to using very high quality RAM so if you upgraded the RAM at some point that could be the cause. There are also other hardware causes too, such as failing third party peripherals such as hard drives, USB hubs etc.)

Software issues can be caused by third party apps that have either modified Mac OS or damaged it or if it is VERY old software perhaps it has not been updated and is now causing conflicts.

So my suggestion is to 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.