Disk Utility finds problem with partition map - but only in safe mode

[Iklatenk]

Disk Utility in normal mode (log in from administrator account) or from Command R shows everything is normal, but when I do it in Safe Mode I get this.

Is this a bug? I wouldn't even know about it if not for random testing using Safe Mode.

When I had Sierra, Disk Utility didn't even want to run in Safe Mode when doing this scan on Apple HDD, just popping window saying the thing about partition map. Back to El Capitan, it now looks like that.

Both in El Capitan and Sierra, running Disk Utility when logging in with admin account or with Command+R, nothing showed up, Disk Utility saying everything is fine. Only in Safe Mode does this appear.

But shouldn't Command+R show the best results - the most precise ones? So is Safe Mode just having a bug of some sort? How often do people run Disk Utility in Safe Mode?

Maybe it is common, no one simply has found out about it.

 

[honestone]

Weird! I just booted my late 2012 Mac MIni, running OS 1012.2, in Safe Mode, and except for the machine taking somewhat longer to boot up, and for the "in red letters" near the right top of my screen that appeared after I logged in ("In safe mode"), I got my normal desktop! I had no idea how to proceed further. So, I shut down the machine, started it up again normally, and this time things went normally, except that the amount of free memory I had (have 4 gig in the machine, and typically have about 2.5 gig after normal startup) was only 512 meg. Fortunately, I have a nifty little app called "Memory Clean 2" that tells me about such memory, and also allows me to free up some more.

Given that I have two other more robust disk cleanup/maintenance/repair programs (TechTool Pro and Disk Warrior), I rarely use Disk Utility for checking up on routine matters. TechTool Pro also has a Partition Map checking feature, and I run it as part of my weekly disk cleanup/maintenance/repair, and backup, processing for both of my machines. It has yet to find any issues. (By the way, via its eDrive feature, I am able to run TechTool Pro in an "isolated", external manner).

Also, given that I use SuperDuper! for making bootable backups, if I need to use Disk Utility (usually when I want to do a clean, "virgin" installation of a Mac OS), I'll re-boot my machine from such a backup and run Disk Utility from there.

 

[honestone]

An update as to what happened with my Mac MIni. After going through what I described above, every time I subsequently started up my Mac, the amount of available memory memory I had (right after logging in, and without running anything except the Finder), was around 500 meg! That was significantly less than what I had consistently been getting before trying out Safe mode, which was about 2.3 gig (out of 4 gig). I looked at Activity Monitor when I had that low amount of available memory, and nothing "jumped out".

So, after saving about 8 critical files/folders, I re-started my Mac Mini from the SuperDuper! backup/clone I had ran on Saturday, used Disk Utility to Erase and Format my internal SSD, launched the OS 10.12.2 installer from there, did a clean, "virgin" installation onto my internal SSD, and used Migration Assistant to "migrate"/copy all my needed "stuff" from that backup. Eventually got to re-starting the machine form the internal SSD, and put the important files I had first saved onto their appropriate locations on the internal SSD. Now things are back to normal.

I of course have no idea why things got messed up after booting to Safe Mode. I am just so thankful that 1) I had the recent SuperDuper! backup, and 2) I have TechTool Pro, which is much better than Disk Utility.

 

[Iklatenk]

Weird! I just booted my late 2012 Mac MIni, running OS 1012.2, in Safe Mode, and except for the machine taking somewhat longer to boot up, and for the "in red letters" near the right top of my screen that appeared after I logged in ("In safe mode"), I got my normal desktop! I had no idea how to proceed further. So, I shut down the machine, started it up again normally, and this time things went normally, except that the amount of free memory I had (have 4 gig in the machine, and typically have about 2.5 gig after normal startup) was only 512 meg. Fortunately, I have a nifty little app called "Memory Clean 2" that tells me about such memory, and also allows me to free up some more.

Given that I have two other more robust disk cleanup/maintenance/repair programs (TechTool Pro and Disk Warrior), I rarely use Disk Utility for checking up on routine matters. TechTool Pro also has a Partition Map checking feature, and I run it as part of my weekly disk cleanup/maintenance/repair, and backup, processing for both of my machines. It has yet to find any issues. (By the way, via its eDrive feature, I am able to run TechTool Pro in an "isolated", external manner).

Also, given that I use SuperDuper! for making bootable backups, if I need to use Disk Utility (usually when I want to do a clean, "virgin" installation of a Mac OS), I'll re-boot my machine from such a backup and run Disk Utility from there.

Hello!

So You are saying Safe Mode in Mac can cause big problems and should not be touched and rather ignored?

 

[honestone]

Hello!

So You are saying Safe Mode in Mac can cause big problems and should not be touched and rather ignored?

I just don't know for sure, but it definitely caused me issues. And, I am very meticulous with disk cleanup/maintenance/repairs, and backups, and I tend to keep my Macs "lean and clean". In fact, I have never needed to boot to Safe Mode. As I stated, given I have TechTool Pro, it does with Disk Utility can do, and then some.

Actually, when you mentioned Sierra, you stated "just popping window saying the thing about partition map". But, with El Capitan, you got that "strange" Partition message (in Safe Mode). Please explain.

And, what Mac model do you have?

 

[Iklatenk]

I just don't know for sure, but it definitely caused me issues. And, I am very meticulous with disk cleanup/maintenance/repairs, and backups, and I tend to keep my Macs "lean and clean". In fact, I have never needed to boot to Safe Mode. As I stated, given I have TechTool Pro, it does with Disk Utility can do, and then some.

Actually, when you mentioned Sierra, you stated "just popping window saying the thing about partition map". But, with El Capitan, you got that "strange" Partition message (in Safe Mode). Please explain.

And, what Mac model do you have?

Safe Mode I only used due to Sierra messing up my display. For some reason (and I saw several posts of other people having same issues), after Sierra, I was unable to access my monitor. Mac booted, sound, but monitor black. I discovered I could access Recovery through CMD+R, then from there restart and then I could log in normally. I tried everything, including Safe Mode and this is where I noticed this.
In the end, I had El Capitan put back by technician and there have been no issues with monitor.

Sorry, my wording was bad. What I mean is, that I got same message in both Sierra and now in El Capitan about "problems were found with partition map that might prevent booting" as it says on that screenshot in my first post. But in Sierra, it refused to run scan at all, just saying that sentence and not running First Aid on Apple HDD.
In El Capitan, it runs first aid as seen on screenshot, then adds that partition comment that worries me.

I do not know if my Mac could have produced same message before Sierra or not as I never touched Safe Mode back then.

My model is Mac mini (Late 2014). Anything more precise I should look up?

 

[honestone]

Hmm, I have a late 2012 Mac Mini, an "almost vintage" Sony 19" monitor, and with Mavericks, through Yosemite, through El Capitan, and now Sierra, I have never had the issues you are encountering. I will say, though, that for my last 3 Mac OS "upgrades" (ie, from Mavericks to Yosemite, then from Yosemite to El Capitan, and recently from El Capitan to Sierra), I did not "upgrade in place". That is, given that I use SuperDuper! for my backups, I booted my Mac Mini (same for my mid 2013 13" MacBook Air) from that SuperDuper! backup, used Disk Utility there to Erase and Format the internal SSD, did a clean, "virgin" installation of the new OS onto the SSD, and then used Migration Assistant to "migrate"/copy all the needed "stuff" from the SuperDuper! backup. Re-started the Mac (either machine) from the SSD, and things were fine (I also needed to do some minor "final" stuff). I also always use the Combo Updater when doing "within the same" OS upgrades.

Of course, whenever I do such upgrades.I first insure that any third party software I use is compatible with the new OS. Quite often, that requires downloading and installing upgrades to such programs. (For Onyx, there is actually a specific version for each Mac OS. I believe there are a couple of other products which have similar upgrade options).

Don't know if it makes a difference, but in case you were using OS 10.12 or 10.12.1, Apple did release OS 10.12.2 a couple of days ago. The combo updater is available from here:

https://support.apple.com/kb/dl1900?locale=en_US

 

[Iklatenk]

Hmm, I have a late 2012 Mac Mini, an "almost vintage" Sony 19" monitor, and with Mavericks, through Yosemite, through El Capitan, and now Sierra, I have never had the issues you are encountering. I will say, though, that for my last 3 Mac OS "upgrades" (ie, from Mavericks to Yosemite, then from Yosemite to El Capitan, and recently from El Capitan to Sierra), I did not "upgrade in place". That is, given that I use SuperDuper! for my backups, I booted my Mac Mini (same for my mid 2013 13" MacBook Air) from that SuperDuper! backup, used Disk Utility there to Erase and Format the internal SSD, did a clean, "virgin" installation of the new OS onto the SSD, and then used Migration Assistant to "migrate"/copy all the needed "stuff" from the SuperDuper! backup. Re-started the Mac (either machine) from the SSD, and things were fine (I also needed to do some minor "final" stuff). I also always use the Combo Updater when doing "within the same" OS upgrades.

Of course, whenever I do such upgrades.I first insure that any third party software I use is compatible with the new OS. Quite often, that requires downloading and installing upgrades to such programs. (For Onyx, there is actually a specific version for each Mac OS. I believe there are a couple of other products which have similar upgrade options).

Don't know if it makes a difference, but in case you were using OS 10.12 or 10.12.1, Apple did release OS 10.12.2 a couple of days ago. The combo updater is available from here:

https://support.apple.com/kb/dl1900?locale=en_US

I never knew this kind of upgrading even existed! Thank you for informing me.

 

[SandJ]

Just to say I have the same error message when using Disk Utility in Safe Mode: https://discussions.apple.com/thread/253836598?page=1