My iMac Retina 4K 21.5 inch late 2015 model has suddenly started crashing.

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Level 1

8 points

My iMac Retina 4K 21.5 inch late 2015 model has suddenly started crashing.

The crashes come in two forms: either I hear the fans briefly working then get a message that my computer is restarting because of a problem; or the screen starts to flicker and then freezes, followed by it restarting. About 3 months ago I swapped out the old fusion drive for an SSD but it has been working fine since then. Grateful for any thoughts on what might be the cause. I've tried restarts and resetting the SMC; and I've disconnected all the peripherals. It's running Monterey 12.7.6

iMac 21.5″, macOS 12.7

Posted on Dec 20, 2024 3:00 AM

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Answer 1

Top-ranking reply

den.thed

Level 10

83,248 points

Dec 20, 2024 6:28 AM in response to Ade-oh

1) Run the Apple Diagnostic Test, as per > Use Apple Diagnostics to test your Mac - Apple Support

2) Download and run the free version of EtreCheckPro, from > https://etrecheck.com/en/index.html

Then post your Report, as per > How to use the Add Text Feature When Post… - Apple Community

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Answer 2

John Galt

Level 10

147,306 points

Dec 23, 2024 4:41 AM in response to Ade-oh

Antivirus software: Apple and F-Secure

Fix that. Remove all non-Apple "anti-virus" / "security" products. Follow their respective uninstallation instructions.

Then, run EtreCheck again to confirm its complete eradication. The EtreCheck report should look exactly like this:

Antivirus software: Apple

Rule 1 of Macs is don't install junk.

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Answer 3

kaz-k

Level 9

50,334 points

Dec 23, 2024 4:09 AM in response to Ade-oh

Hi,

I just wonder if kernel panic occurs on both, macOS and Windows operating systems.

If kernel panic occurs only on macOS, try to start up in Safe mode, then normal boot which could solve your issue.

Start up your Mac in safe mode – Apple Support (AU)

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Answer 4

den.thed

Level 10

83,248 points

Dec 23, 2024 7:36 AM in response to Ade-oh

I agree 100% with John Galt.

You need to completely uninstall F-Secure as per the developers instructions.

Then use Safe Mode followed by a normal restart.

see > Start up your Mac in safe mode - Apple Support

If you continue to have problems after that...

What RAM modules were used, when you upgraded to the 4T EVO SSD and 16GB of RAM...?

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Answer 5

rkaufmann87

Level 10

144,862 points

Dec 23, 2024 9:26 AM in response to Ade-oh

As a general rule of thumb NEVER EVER install the following types of third party apps:

Antivirus
Cleaning
Security
Maintenance
VPN

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Answer 6

John Galt

Level 10

147,306 points

Dec 23, 2024 8:45 AM in response to den.thed

disk0 - Samsung SSD 870 EVO 4TB 4.00 TB (Solid State - TRIM: No)

I overlooked that part of the report. The Samdung "EVO" series SSDs do not enjoy a good reputation among Mac users, and is more likely to be the reason for the KP and app crashes.

"F-Secure" should still be removed of course.

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Answer 7

den.thed

Level 10

83,248 points

Dec 23, 2024 9:10 AM in response to John Galt

John Galt wrote:

The Samdung "EVO" series SSDs do not enjoy a good reputation among Mac users, and is more likely to be the reason for the KP and app crashes.

I agree!

I would have chosen a 2.5" SATA OWC, Crucial, WD or even a PNY SSD which I've had good luck with.

Plus I would only use OWC or Crucial RAM to upgrade Mac systems.

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Answer 8

Ade-oh Author

Level 1

8 points

Dec 23, 2024 9:34 AM in response to rkaufmann87

Yes. I wouldn't have done but my employer mandates - and pays for - the F-Secure VPN for personal electronic devices when travelling - which I do a lot. I haven't had any issues with iPhones or MacBooks so assumed it would be OK on the iMac: clearly not.

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