Short answer
A reported macOS 27 bug causes dasd and appstoreagent to spike at midnight and pin a CPU core for hours, producing overnight heat, fan noise, and battery drain. The reported cause is a stuck Apple Arcade scheduler date. Confirm it via Activity Monitor and a Terminal date check, then apply the community workaround.
What it looks like
You close the lid on a healthy battery. In the morning the Mac is warm, the fans have clearly been busy overnight, and the charge has dropped further than a night of sleep should cost. If this started right after upgrading to macOS 27 Golden Gate, there is a specific suspect: two background processes called dasd and appstoreagent locked in a tight loop, reportedly starting at midnight local time.
A MacRumors thread from September 27 documents the pattern across MacBook Pro, MacBook Air, and Mac Studio machines. One user left two Macs running overnight with a system monitor open and watched the load drop at 9 AM. Another noted you may never see the CPU load without a monitor, but you will notice the battery draining faster.
The reported cause: a deadline that never moves
appstoreagent is the App Store's background helper. It checks for updates, handles downloads, and does bookkeeping for Apple Arcade. dasd is the Duet Activity Scheduler, the daemon that decides which background maintenance tasks run and when.
Two independent investigators traced the loop to the same place: an Apple Arcade task called ArcadeResetPO. After it runs, a preference named ArcadePayoutResetDate should advance to the next cycle. Instead it stays stuck on a past date. The scheduler sees the task as overdue and runs it immediately, the agent re-registers it with the same expired time, and the cycle repeats roughly 70 to 100 times per second. The result is one pinned core, heavy logging, heat, and battery drain.
Confirm it in two minutes
Nothing here changes any setting. Run these while the Mac is misbehaving, ideally first thing in the morning.
- Open Activity Monitor, click the CPU tab, sort by % CPU. Look for
dasdandappstoreagentnear the top with sustained CPU. A value near 100% for one process on a multi-core Mac is the pattern. - In Terminal, compare the stored Arcade date against the current time:
plutil -extract ArcadePayoutResetDate raw ~/Library/Preferences/com.apple.appstored.plist
date -u +"%Y-%m-%dT%H:%M:%SZ"If the stored date is in the past while those processes are busy, that matches the reported bug. If it is in the future and the processes are quiet, this bug is not what is happening to you. If the key does not exist, the Mac may never have launched the App Store or Apple Arcade, which is not evidence either way.
The community fix and what Apple has not said
The reported workaround is one defaults write to push the date into the future, followed by killall appstoreagent. It is reversible and reportedly holds for as long as the date you choose. Whether macOS 27.0.1 fixes the underlying bug is unconfirmed, so verify on your own Mac rather than assuming the update resolved it.
What Smart Breeze shows you
This is exactly the kind of problem a temperature history makes obvious. If your Mac is hot at 3 AM with the lid closed, Smart Breeze shows the spike and which sensor is climbing, so you can tell a runaway background process apart from normal post-upgrade indexing. A fan curve cannot fix a stuck scheduler task; identifying the cause is the fix.
Sources and scope
Primary references and product scope
Apple sources define macOS and hardware behavior. Smart Breeze behavior is checked against the signed release and its documented safety boundaries. Where a conclusion is an inference or a method, this guide labels it as such.
See the spike
Catch overnight heat with a temperature history
Smart Breeze records local temperature trends on-device, so a 3 AM runaway process shows up as a pattern, not a mystery.