Both Apple Mail and Safari have started quitting silently in the background when hidden, where “hidden” can mean:

  • the app is hidden,
  • a different app is in full screen mode, or
  • the machine goes to sleep.

It appears to happen very near the 5 minute mark.

It doesn’t happen if the app has visible windows. But, like a furtive pet, as soon as it thinks I’m not looking, away it goes.

It appears to be a quit, not a crash; there is no crash alert, and no crash log in Diagnostic Reports in Console. I suspect the apps are doing this intentionally to save resources. It may also apply to other Apple apps; I haven’t investigated.

While this might be a case of “feature, not bug!,” it’s a pain for me. Mail launches slowly enough that relaunching it is a pain, and I also rely on it applying filters in the background when I’m away from the laptop in order to keep my inbox tidy when looking at message on my phone. As for Safari, it occasionally loses valuable state in open web pages — the position I’d scrolled to in an article, for example.

These lines from the system log seem potentially relevant, but they appear to only be cleaning up the app’s caches:

default 13:32:30.182353-0600    deleted Updating configuration of monitor <RBSProcessMonitorConfiguration| id:M4184-13039 qos:17 predicates:[<RBSProcessPredicate <RBSProcessBundleIdentifierPredicate "com.apple.mail">>] descriptor:<RBSProcessStateDescriptor| values:5> events:0x0>
default 13:32:30.183182-0600    runningboardd   Received termination request from [daemon<com.apple.cache_delete(502)>:4184] on <RBSProcessPredicate <RBSProcessBundleIdentifierPredicate "com.apple.mail">> with context <RBSTerminateContext| code:0xBADDD15C explanation:CacheDeleteAppContainerCaches requesting termination assertion for com.apple.mail reportType:None maxTerminationResistance:NonInteractive attrs:[
    <RBSPreventLaunchLimitation| <RBSProcessPredicate <RBSProcessBundleIdentifierPredicate "com.apple.mail">>>
default 13:32:30.687185-0600    runningboardd   Acquiring assertion targeting system from originator [daemon<com.apple.cache_delete(502)>:4184] with description <RBSAssertionDescriptor| "CacheDeleteAppContainerCaches requesting termination assertion for com.apple.mail" ID:362-4184-657504 target:system attributes:[
    <RBSPreventLaunchLimitation| <RBSProcessPredicate <RBSProcessBundleIdentifierPredicate "com.apple.mail">>>
default 13:32:30.687778-0600    runningboardd   Executing termination request for: <RBSProcessPredicate <RBSProcessBundleIdentifierPredicate "com.apple.mail">>
default 13:32:30.690107-0600    deleted got termination assertion for: com.apple.mail
default 13:32:30.728913-0600    deleted 362 com.apple.mail purging cache, self.lastKnownCacheSize: 4096 at Wed Jan  5 13:32:30 2022
default 13:32:30.730783-0600    deleted 398 clearCaches result: 4096 for com.apple.mail on <private>

Anybody know what’s happening? Is there any way to disable this?

This is on macOS 12.0.1, 16” 2019 MBP. I suspect it started about the time of my Monterey upgrade.

  • 1
    For most Monterey issues, seeing if 12.1 fixes it would always be prime first test.
    – Tetsujin
    Jan 5, 2022 at 19:43
  • Ah, good point. I hadn’t noticed it wasn’t installing due to disk space. Will try and report back! Jan 5, 2022 at 19:45
  • That sounds like you are running under high memory pressure - what does Activity Monitor show and what machine and memory are you using
    – mmmmmm
    Jan 5, 2022 at 21:38
  • 1
    I've been having this problem, with a variety of apps, since 12.0. It persists under 12.2.1. It's infuriating, and I would love to find a solution.
    – zygoat
    Mar 1, 2022 at 20:25
  • 1
    @bmike Yep, I think that was the culprit. A couple of weeks ago, I moved my iPhone backups to another machine, freeing up about 140 GB… and the problems have stopped.
    – zygoat
    Jun 10, 2022 at 16:19

2 Answers 2


I am also facing this issue on a 2018 mac mini. I think this is because of low disk space as the logs indicate that the process was terminated to clean it's caches.

I think it got fixed for the OP because they cleaned their disk and might still have enough disk space to prevent this from triggering.

  • Super observation + I figured it was app nap / sudden termination, but storage pressure could trigger this as well.
    – bmike
    Jun 9, 2022 at 9:25

I ended up running into this problem with some of my apps and narrowed down the cause to a specific system framework, CacheDelete.framework, which is designed to delete caches in an attempt to reclaim disk space.

There is a lot more info in the linked post below, but the high level overview is this is an intended behavior of the system when available disk space is deemed to be low enough that "purgeable" space should be recovered. The same code is also run as a result of purgeable space recovery by apps such as CleanMyMac.

Read more here:


  • This basically is a link-only answer as the main answer is hiding behind the link. Can you summarize the linked page so people can read the answer directly on AD?
    – nohillside
    Jun 18, 2022 at 17:58
  • I was reading your blog and coming here to be sure things link up, only to find you’re here already. Thanks for the prose explanation and discovery that cleaning utilities can trigger this. Does deleted fire up and use CPU at all when the cleaning happens?
    – bmike
    Jun 19, 2022 at 14:14
  • @nohillside Sorry if it was an inappropriate use of answers. I can move it to a comment on the original post. I don't want to summarize the post but if anybody else wants to of course I don't mind. Jun 19, 2022 at 19:08
  • @bmike Glad you enjoyed the post. I don't know about how much CPU is used when the cleaning happens. I assume it's not too much but don't know for sure. Jun 19, 2022 at 19:08
  • The problem with answers relying on links is that the answer becomes useless if they break. So at least a short TL;DR summary might help. But it‘s fine either way.
    – nohillside
    Jun 19, 2022 at 19:58

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