Not able to update to 10.16 Beta2

I cannot update to Beta2 of Big Sur (from beta1) updater in system preferences breaks with an error. command-line tool brakes with

Code Block Failed to download & prepare update: Error Domain=SUMacControllerError Code=7722 "[SUMacControllerErrorPreflightPrerequisiteCheckFailed=7722] Failed to perform PreflightPrerequisite operation: com.apple.MobileSoftwareUpdate.preflight.error(Preflight):MSUPreflightErrorTargetIsNotSnapshotBooted(6) | The volume can not be used because it is not snapshot booted.
-> Current device configuration requires an alternate installer to perform the update.: [com.apple.MobileSoftwareUpdate.preflight.error(Preflight):MSUPreflightErrorTargetIsNotSnapshotBooted(6)|Unknown Error Indication|]" UserInfo={SUMacControllerErrorIndicationsSummary=|Unknown Error Indication|, SUMacControllerErrorIndicationsMask=8, SUMacControllerErrorIndicationsDescription=-> Current device configuration requires an alternate installer to perform the update., NSUnderlyingError=0x7f93f34051d0 {Error Domain=com.apple.MobileSoftwareUpdate.preflight.error Code=6 "The volume can not be used because it is not snapshot booted." UserInfo={NSLocalizedDescription=The volume can not be used because it is not snapshot booted., NSLocalizedFailureReason=The volume can not be used because it is not snapshot booted., MSUPreflightAlternateInstallerRecommended=true}}, NSDebugDescription=[SUMacControllerErrorPreflightPrerequisiteCheckFailed=7722] Failed to perform PreflightPrerequisite operation: com.apple.MobileSoftwareUpdate.preflight.error(Preflight):MSUPreflightErrorTargetIsNotSnapshotBooted(6) | The volume can not be used because it is not snapshot booted.
-> Current device configuration requires an alternate installer to perform the update.: [com.apple.MobileSoftwareUpdate.preflight.error(Preflight):MSUPreflightErrorTargetIsNotSnapshotBooted(6)|Unknown Error Indication|], NSLocalizedDescription=Current device configuration and target is invalid for install in the current state. Please try again.}

Any Ideas on that?
Answered by michis_0806 in 619498022
I think I fixed it, but I don't know exactly what part did the trick:
  1. reboot into recovery

  2. first help on system-disks

  3. setting startup security to high

  4. restarted into Big Sur and Update runs without any error

Accepted Answer
I think I fixed it, but I don't know exactly what part did the trick:
  1. reboot into recovery

  2. first help on system-disks

  3. setting startup security to high

  4. restarted into Big Sur and Update runs without any error

I believe this only works with T2-enabled portables, I cannot find this option on my older MacBook Pro.

Any other suggestions?
Alright so I took a look at this on my side and just doing first aid on the disks doesn't help.

Since I'm not comfortable with changing the startup security to high (it bricked my computer 3 times when I did that during Catalina Beta) I tried something that sounded more safe and doesn't require any changes to your system...

Restart your computer and hold the shift key to boot into safe mode and then start the update from there.

Worked wonders for me with startup security to none...

I'm now on Beta 2 :D
Thank you michis_0806, you workaround works for my T2-enabled MacBook Pro.
Thanks @michis_0806. It fixed update problem for my MacBookPro15,1. It was enough to set "Medium" level of stratup Security for me.
Thank you @GoD+Brutus, your suggestion was working well for me.

But, the download process was very slow. Need more patient.
Not able to update to 10.16 Beta2
 
 
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