Pick your Panacea: how to select a generic fix

Sometimes you’re lucky, and there’s an obvious specific solution to a macOS problem. If an app fails to open, you may find that deleting it and reinstalling the app does the trick. But macOS is fiendishly complex, and diagnosing many problems is often a problem in itself. Trying a generic solution or universal panacea often seems the only way ahead.

This article is a brief guide to the ten most popular panaceas, or quick fixes, which are often used to fix problems without getting a detailed diagnosis – when to use them, how they work, and whether they’re worth it:

  • Restart
  • Run a malware checker
  • Restart in Safe mode
  • Run hardware diagnostics
  • Reset SMC, NVRAM
  • First Aid on boot disk
  • Repair permissions on Home folder
  • Install latest Combo update
  • Create a new user
  • Re-install macOS

Startup and shutdown key combinations


If something stops working properly, restarting your Mac is usually an excellent first step. It’s simple, quick, and almost always available. I have known it cure everything from trackpad/mouse problems to lost ethernet connections. The only occasions for which it is not an appropriate action are if you think there is any chance that you might have malware active, or incipient hardware failure. If your graphics adaptor is starting to fail, then restarting may turn a limping Mac into a dead one, although you’re almost certainly going to have to restart to run hardware diagnostics.

If something in software has been working correctly and then stops, restarting loads macOS and all its myriad extensions afresh, and should, if you’re lucky, put everything back to normal again. In my experience, it also has a high success rate. It doesn’t, though, help you much in working out what went wrong, so you’ll be left hoping that it doesn’t go wrong again.

For many well-known issues, a restart is also the only cure. A good example is the bug in Sierra which can stop Time Machine backups from running automatically.

Run a malware checker

Odd behaviour, particularly in or around your browser, or following a recent download of any kind, should take you straight to the software which you use to check for malware and its infections. Ideally, you should be running protection which keeps a lookout for the first signs of malware, including changes made to sensitive folders such as the LaunchAgents and LaunchDaemons folders in each Library.

If you have a good malware checker, this should only take a couple of minutes at most, and is always time well spent. Malware is not the only cause of oddity in behaviour – macOS can be pretty strange at times – but it is better to run a check a couple of times a day than get caught out once in a blue moon.

Not only that, but good protection is also able to remove most malware there and then, which would solve the problem. There are several excellent tools, from Objective-See, Sqwarq, and Malwarebytes, for example, so there is no excuse.

Restart in Safe mode

Starting up with the Shift key held down, to engage Safe mode, is a wise move if a simple restart doesn’t clear a problem as you’d expect it to. It’s also the first choice when you suspect that your problems might be the result of incompatible extensions, or other software which is loaded automatically.

Apple doesn’t detail exactly what is different in Safe mode, but lists the following broad categories:

  • The startup disk is checked, and any necessary repairs are made to it before going any further.
  • A subset of kernel extensions is loaded, which reduces the chances of any conflicting. Unfortunately, this also disables quite a lot of functionality, particularly with third-party hardware, which may rely on the loading of its extension(s) to work.
  • Blocks startup and login items from being loaded automatically. Again, this may have functional impact.
  • Disables user-installed fonts. Although font problems are now unusual, this should eliminate them completely.
  • Deletes many macOS caches, including those for fonts, the kernel cache, and others. This can eliminate problems which might otherwise persist through a restart.

In theory, if a problem vanishes after starting up in Safe mode, you should be able to pin it down to one of those areas. In practice, so much is disabled, or limps along only partially functional, that Safe mode is now of more limited value. Sometimes, clearing caches in Safe mode is all that is required to fix the problem, and once you have restarted back into normal mode, the problem has gone away.

Because it’s quick and non-destructive to almost everything apart from those caches, restarting in Safe mode is a good thing to do early on when tackling a problem. But don’t expect it to make your Mac magically better.

Further information

Run hardware diagnostics

Restarting in Diagnostic or Apple Hardware Test mode can’t fix anything in your Mac, but it can put your mind at rest if there’s any suspicion that your problems could be caused a developing hardware fault. For some issues, like display glitches, running hardware diagnostics should be one of the first things that you try.

At the same time, it’s not unusual for these basic tests to miss a fault which only shows up when the full diagnostics are run in a Genius Bar. Remember that completing hardware tests without encountering a fault doesn’t prove that your Mac is flawless, but it does make a hardware repair much less likely.

Further information


Some users are apt to reset the SMC and NVRAM at the slightest glitch, often for the least appropriate reason. Although doing so is not harmful, to reset them properly takes a fair bit of faffing around, and is not something to do each lunchtime just for the hell of it.

Good reasons for resetting these are odd behaviour of hardware ancillaries like cooling fans, display modes, sleeping and waking, audio volume, etc. They are most easily reset together, and unless you have good reason not to do so, you should normally reset the SMC first, then the NVRAM. If you guessed right, then this action will bring instant cure, but most resets don’t actually achieve anything useful.

Further information

First Aid on boot disk

If you think that you might have a problem on your boot volume, running First Aid in Disk Utility is an obvious first step. It’s also a good measure before trying other panaceas: to have confidence that your startup disk is in good shape is valuable.

If you’re going to do this, though, do it properly: restart in Recovery mode and run Disk Utility from there. Trying to check and repair a live filesystem is not ideal, and you will get a more thorough check and better repair when this is performed from a separate startup volume, such as the Recovery partition.

If First Aid does detect and repair a problem, chances are that is an incidental finding, and won’t do anything to help directly. But, like running hardware diagnostics, it can improve your confidence in trying something else.

Further information

Repair permissions on Home folder

Before El Capitan, repairing permissions of system folders was a standard panacea which had once been an excellent cure-all. This seems to have been the result of bugs in installers, and elsewhere, which could readily lead to corruption of system and other files.

Repairing permissions has returned as a valuable panacea. Now that macOS system files are almost entirely locked away by SIP, it is not their permissions which are under suspicion, but those of the many files clustered in your Home folder Library, particularly preference files.

Apple’s list of symptoms which make repairing permissions a panacea is long and disparate, and includes:

  • changes to preference settings, particularly those for System Preferences, do not ‘stick’;
  • changes made to the Dock do not ‘stick’;
  • you are asked to authenticate when trying to move or alter some folders in your Home folder;
  • when trying to save, you are told that the file is locked, or that you don’t have permission;
  • Preview, TextEdit, and App Store apps (which are sandboxed) may crash when opened;
  • alerts warning that the startup disk has no more space available for app memory;
  • Safari or SafariDAVClient use large amounts of resources (memory);
  • your Mac runs very slowly;
  • iTunes cannot sync a device;
  • problems with Photos or iPhoto libraries, including inability to import into the library, or forgetting the library each time the app is opened.

Since this has been advocated, many users have found the new way of repairing permissions has solved otherwise intractable problems. But if your problem is not one of those listed, don’t have high expectations. Performed properly, it shouldn’t do any harm, as it only sets permissions to what they should be.

Further information

Install latest Combo update

Anything that breaks soon after a macOS or similar update is likely to be a problem caused by that update, although that is by no means guaranteed. One potentially curative treatment for such problems is to download and install the latest Combo update.

With each macOS update (except the first after a major upgrade), Apple provides two different standalone updates: the delta, which takes you up just one step, from the previous version, and the Combo, which takes any older version up to the new release. The Combo updater includes all the files which have changed since the initial release, making it much larger than the delta update, but capable of fixing most problems which might have arisen since the initial install.

System installers are complex, and every once in a while they get it wrong, or there is a glitch during updating. That can leave your Mac with a partial update, with components that are incompatible. The Combo updater should fix those in one fell swoop.

Installing the most recent Combo update should never do any harm, although it quite often doesn’t change or fix anything either. If your problem arose soon after a macOS or similar update, it should be high on your list of potential solutions.

Further information

Create a new user

If the software/file causing a problem is lurking in the Library of your Home folder, then an excellent way of eliminating that is to create a new user, and do what you need to from that clean user account.

This not only takes time, but uses storage space too. Worse, you’ll find that using many of your apps from a second user account is more difficult, and can sometimes prove impossible on a normal single-user licence. This is therefore a better solution if only a single app is involved, and you can isolate it from your normal workflow. You can then log in as that second user, run the app to process as many documents as needed, and switch back to your normal user account.

If you can, use this as a diagnostic step rather than a solution. Once you’ve established that the problem vanishes in that second user account, work through the settings and Home folder of the first account to identify what was causing your problems in the first place.

Further information

Re-install macOS

Some other operating systems – you can guess which, perhaps – seem to benefit from being re-installed quite frequently. macOS is not one of them. I cannot recall ever re-installing macOS as a means of solving a problem. Many Macs are worked hard during the day, and restarted every few days, yet never need macOS to be re-installed.

The exceptions to this are few and far between. If you turn SIP off and mess with your system files, then re-installing may be the only way to recover your Mac’s sanity. Now, with SIP turned on, you can still create havoc with third-party extensions and the like. But they are relatively straightforward to fix, and in many cases are quite independent of macOS.

Re-installing macOS takes a long time, and runs the real risk that, somewhere in the process, important or sensitive files will get lost or mangled, only making your problems worse.

Further information
Reinstalling macOS changed with 10.12.4