MacOs BigSur update 11.2.3 hangs with Error Domain=SUMacControllerError Code=7749 in logfile My iMac (Retina 5K, 27&quot;, 2020) is not updating to latest MacOS BigSur 11.2.3 from 11.1.
It hangs in the UI with &quot;10 minutes left&quot; in the progress bar.
The install.log file exposes the following error messages (see below). Any idea what could cause this issue? Found nothing on google for the error message.
021-03-13 20:25:03+01 imac-ts SoftwareUpdateNotificationManager[764]: Successful call to queueAutoUpdatesForLaterWithCompletionHandler
2021-03-13 20:25:03+01 imac-ts SoftwareUpdateNotificationManager[764]: SUAppStoreUpdateController: install later for &lt;none&gt;
2021-03-13 20:25:03+01 imac-ts SoftwareUpdateNotificationManager[764]: SUAppStoreUpdateController: Triggering user side stash early for later updates
2021-03-13 20:25:03+01 imac-ts softwareupdated[273]: No keys specified for install-later registration
2021-03-13 20:25:03+01 imac-ts SoftwareUpdateNotificationManager[764]: SUOSUAuthenticationManager: No LocalAuth required
2021-03-13 20:25:03+01 imac-ts softwareupdated[273]: Queued (
      &quot;&lt;SUOSUProduct: MSU_UPDATE_20D91_patch_11.2.3&gt;&quot;
    ) for later
2021-03-13 20:25:03+01 imac-ts SoftwareUpdateNotificationManager[764]: SUOSUShimController: Armed: 1, with mode: 1, date: (null), updates queued for later: (
      &quot;&lt;SUOSUProduct: MSU_UPDATE_20D91_patch_11.2.3&gt;&quot;
    )
2021-03-13 20:25:03+01 imac-ts SoftwareUpdateNotificationManager[764]: Failed to create stash &amp; update local policies: Error Domain=SUMacControllerError Code=7749 &quot;[SUMacControllerErrorCommitStashInvalidState=7749] Committing the stash requires a valid prepare yet none is currently available (currently preparing)&quot; UserInfo={NSDebugDescription=[SUMacControllerErrorCommitStashInvalidState=7749] Committing the stash requires a valid prepare yet none is currently available (currently preparing), NSLocalizedDescription=Sichern der Benutzeranmeldedaten f&lt;C3&gt;&lt;BC&gt;r das Softwareupdate zurzeit nicht m&lt;C3&gt;&lt;B6&gt;glich.}
2021-03-13 20:25:03+01 imac-ts SoftwareUpdateNotificationManager[764]: Successful call to queueAutoUpdatesForLaterWithCompletionHandler
The solution to this was constantly trying to reboot.
I have left the Mac between 1 and 3 hrs between different attempts.
Then stopped the round and rebooted, retry.
On third attempt the OS was finally installed.
I do not know what the problem was.