Hi, I've had this same issue ever since upgrading to Big Sur a month ago. Launchd fires kmutil load -b com.apple.fsplaceholder every 10 seconds, causing kernelmanagerd to be my top 2 CPU user. The following tricks have not helped: Booting without 3rd party kexts with Cmd+S¹ Resetting NVRAM, as suggested on MacRumors forums Quitting Dropbox, Google Drive, pCloud Drive and Keybase Delete deprecated /Library/Extensions/Dropbox.kext sudo kmutil install --check-rebuild and sudo kmutil install --update-all, which fails with: failed to build release collection: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted" sudo launchctl unload /System/Library/LaunchDaemons/com.apple.applefsplaceholder.plist, which fails: Operation not permitted while System Integrity Protection is engaged ¹ I thought this would be safe mode, but is actually single-user mode, which should be disabled but in fact booted with no 3rd party kexts loaded. Safe mode (hold shift) does not work as I've forgotten my EFI password 😅 However, just once I got kernelmanagerd to quiet down by starting Dropbox. I crudely checked that Dropbox (and VMware) have linkings against com.apple.fsplaceholder: /Library $ sudo grep -i fsplaceholder -R . Binary file ./Apple/System/Library/Receipts/com.apple.files.data-template.bom matches Binary file ./DropboxHelperTools//Dropbox_u501/dbkextd matches /Applications $ sudo grep -i fsplaceholder -R . Binary file ./Dropbox.app/Contents/XPCServices/InfiniteProxyHelper.xpc/Contents/MacOS/InfiniteProxyHelper matches Binary file ./Dropbox.app/Contents/XPCServices/InfiniteProxyHelper.xpc/Contents/embedded.provisionprofile matches Binary file ./Dropbox.app/Contents/Frameworks/python-extensions/macinfinite_native.cpython-38-darwin.so matches Binary file ./VMware Fusion.app/Contents/Library/vkd/spherelet-initrd matches Here's my 3rd party kexts, after removing two from unidentified developers. Attached is one round of kernelmanagerd insistently checking extensions. kernelmanagerd-kmutil-fsplaceholder.log

Hello I Fixed this by deleting them nasty smelling file: $ ls -l /Library/Preferences/com.apple.fsplaceholder/ -rw-r--r--  1 root wheel   0 May 21 18:43 com.dropbox.user.98ecb765c7491ca8a181eaacc2aeac1ce7fd0c4a Restarted Dropbox, and it hasn't come back as of yet. Thanks, Dropbox.. -- I realised that /System/Library/LaunchDaemons/com.apple.applefsplaceholder.plist has: <key>QueueDirectories</key> <array> <string>/Library/Preferences/com.apple.fsplaceholder</string> </array> …and from man launchd.plist: QueueDirectories <array of strings> This optional key keeps the job alive as long as the directory or directories specified are not empty. Huh 🤪