Scheduled tasks on the current TP5 of Windows Server 2016, which have a CalendarTrigger with repetition configured, don't seem to trigger and cannot be started manually.
The same trigger without repetition (e.g. after unchecking the "Repeat task every:" checkbox in taskschd.msc) works correctly.
A TimeTrigger with the same repetition configuration works, too.
taskschd.msc calculates and displays the next runtime correctly.

When I try to start such a task manually in taskschd.msc, a message box appears (running any other task works):
de-DE: "Der Aufgabenplanungsdienst ist nicht verfügbar. Die Aufgabenplanung wird erneut versuchen, eine Verbindung herzustellen."
en-US: "Task Scheduler service is not available. Task Scheduler will attempt to reconnect to it."

When I try to start the task by using Start-ScheduledTask, a non-terminating exception is thrown ("Nicht implementiert"="Not Implemented"):
PS C:\Users\Administrator> Start-ScheduledTask -TaskName bad
Start-ScheduledTask : Nicht implementiert
In Zeile:1 Zeichen:1
+ Start-ScheduledTask -TaskName bad
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (PS_ScheduledTask:Root/Microsoft/...S_ScheduledTask) [Start-ScheduledTask]
, CimException
+ FullyQualifiedErrorId : HRESULT 0x80004001,Start-ScheduledTask

When I try to start it via schtasks.exe, the same message appears:
C:\Users\Administrator>schtasks /run /tn bad
FEHLER: Nicht implementiert

When the task should trigger by time, there are no events in Microsoft-Windows-TaskScheduler/Operational indicating any activity around this task.

The tasks trigger sections look like this:
working (without repetition):
<Triggers>
<CalendarTrigger>
<StartBoundary>2016-06-14T00:13:00</StartBoundary>
<Enabled>true</Enabled>
<ScheduleByDay>
<DaysInterval>1</DaysInterval>
</ScheduleByDay>
</CalendarTrigger>
</Triggers>
not working (with hourly repetion):
<Triggers>
<CalendarTrigger>
<Repetition>
<Interval>PT1H</Interval>
<Duration>P1D</Duration>
<StopAtDurationEnd>false</StopAtDurationEnd>
</Repetition>
<StartBoundary>2016-06-14T00:13:00</StartBoundary>
<Enabled>true</Enabled>
<ScheduleByDay>
<DaysInterval>1</DaysInterval>
</ScheduleByDay>
</CalendarTrigger>
</Triggers>

On Windows Server 2012R2 this task works perfectly fine.

Test environment (in case it matters):
Hyper-V Generation 2 VMs on Windows Server 2012R2
Windows Server 2016 Technical Preview 5 Standard with GUI German (installed from de_windows_server_2016_technical_preview_5_x64_dvd_8512319.iso, SHA1 20B276A6EF63AB46FF50A561CD16B48FDF8787AE)
3 VMs, 2 of them fresh installs without any modification except the task

The whole task:
<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.4" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
<RegistrationInfo>
<Date>2016-06-14T10:20:18.9077118</Date>
<Author>WIN-B5GC2VET9K1\Administrator</Author>
<URI>\Test</URI>
</RegistrationInfo>
<Triggers>
<CalendarTrigger>
<Repetition>
<Interval>PT1H</Interval>
<Duration>P1D</Duration>
<StopAtDurationEnd>false</StopAtDurationEnd>
</Repetition>
<StartBoundary>2016-06-14T00:13:00</StartBoundary>
<Enabled>true</Enabled>
<ScheduleByDay>
<DaysInterval>1</DaysInterval>
</ScheduleByDay>
</CalendarTrigger>
</Triggers>
<Principals>
<Principal id="Author">
<UserId>S-1-5-18</UserId>
<RunLevel>LeastPrivilege</RunLevel>
</Principal>
</Principals>
<Settings>
<MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>
<DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries>
<StopIfGoingOnBatteries>true</StopIfGoingOnBatteries>
<AllowHardTerminate>true</AllowHardTerminate>
<StartWhenAvailable>false</StartWhenAvailable>
<RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>
<IdleSettings>
<StopOnIdleEnd>true</StopOnIdleEnd>
<RestartOnIdle>false</RestartOnIdle>
</IdleSettings>
<AllowStartOnDemand>true</AllowStartOnDemand>
<Enabled>true</Enabled>
<Hidden>true</Hidden>
<RunOnlyIfIdle>false</RunOnlyIfIdle>
<DisallowStartOnRemoteAppSession>false</DisallowStartOnRemoteAppSession>
<UseUnifiedSchedulingEngine>false</UseUnifiedSchedulingEngine>
<WakeToRun>false</WakeToRun>
<ExecutionTimeLimit>PT72H</ExecutionTimeLimit>
<Priority>7</Priority>
</Settings>
<Actions Context="Author">
<Exec>
<Command>C:\temp\test.bat</Command>
</Exec>
</Actions>
</Task>

Repro 1:
1) browse around the file system or any zip files, double click on any .txt files you find to read them.
2) Click 'X' in the top right of notepad to close out of notepad.

Repro 2:
1) open explorer and click on "Documents" in the treeview to show your documents (and a folder you should definitely have permissions to).
2) In the area showing your folders and files, right click and choose to create a new text document. (I named it test.txt)
3) Double click the new text file and add some text. (I wrote "hello")
4) Select 'File' -> 'Save'
5) Click the 'X' at the top right of Notepad or, Select 'File' -> 'Exit' to close it.

Result:
Notepad crashes.

Details:
Unhandled exception at 0x.... (ntdll.dll) in notepad.exe 0x... "Access violation reading location 0x0000000000000000"

Expected:
No crashing bugs.

Environment:
Clean Win Server 2016 TP5 - Build 14300.rs1_release_svc.160324-1723
the machine is joined to an AD domain.
user is logged on with a domain account.

When using the startmenu in fullscreen mode, the start menu won't open anymore after a restart. When you disable and re-enable fullscreen mode, it works once again until the next restart.

It seems to be the ShellExperienceHost:

Name der fehlerhaften Anwendung: ShellExperienceHost.exe, Version: 10.0.14393.447, Zeitstempel: 0x5819bf85
Name des fehlerhaften Moduls: StartUI.dll, Version: 10.0.14393.447, Zeitstempel: 0x5819be04
Ausnahmecode: 0xc0000005
Fehleroffset: 0x00000000000b96b0
ID des fehlerhaften Prozesses: 0xa50
Startzeit der fehlerhaften Anwendung: 0x01d2ecced8231441
Pfad der fehlerhaften Anwendung: C:\Windows\SystemApps\ShellExperienceHost_cw5n1h2txyewy\ShellExperienceHost.exe
Pfad des fehlerhaften Moduls: C:\Windows\ShellExperiences\StartUI.dll
Berichtskennung: 563781c7-6fab-49ae-b3de-e0dd30c1c08c
Vollständiger Name des fehlerhaften Pakets: Microsoft.Windows.ShellExperienceHost_10.0.14393.447_neutral_neutral_cw5n1h2txyewy
Anwendungs-ID, die relativ zum fehlerhaften Paket ist: App

It's also possible that this happens only to local admins.

Derived from this thread:
https://social.technet.microsoft.com/Forums/windows/en-US/5703e7b0-433a-4347-a572-a6da7938f35d/startmenu-wont-open-if-fullscreen-is-enabled?forum=ws2016

A hotfix was created by Microsoft to prevent further leaked redirected printers from accumulating in the registry. https://support.microsoft.com/en-us/kb/2620656
Unfortunately, according to the script provided in that KB article the hotfix only deals with the redirected printers that have "session" in the name. The issue is that Microsoft changed this a long time ago to now have "redirected" in the name instead as well as the format of the name being different.
This means that the redirected printers with the new name format are still being leaked in the registry causing the same issue. Note that this is also proven simply by reviewing the affected registry keys after logging in and out a few times.
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Devices
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\PrinterPorts

Note that although the KB article applies to Windows 7, Windows Server 2008 R2, Windows Vista, and Windows Server 2008, it still happens in Windows Server 2012 and Windows Server 2012 R2 and likely also in Windows 8 through Windows 10.

Please stop the leaked printer names to eliminate the problem with many software products out there.

Thank you.

Cross-posted from Technet forums:

I think we've identified a bug in Server 2016. Long story short:
1. Open lusrmgr.msc
2. Set an active users' properties to require password change at next logon
3. Reboot (or just logout, haven't tried that)
4. Press Ctrl+Alt+Del to logon, enter user's current password
5. Press Cancel when informed you need to change your password
6. Press Ctrl+Alt+Del again, enter user's current password, proceed 7. with password change (notice username is blank at this point)
8. Password gets changed but you are returned to the change password screen with no way to go back or proceed
9. Forced reboot appears to be the only way out but you can logon normally after this

We discovered this when running through the sysprep process and had bypassed the standard OOBE set password screen. Windows Server still wants the password set at first logon so we end up setting the password in the standard password change method instead of via OOBE. I realized this wasn't just a problem with our OOBE process though because just checking the box in user properties will make it happen. Tested this on the built-in Administrator account and a standard account I created after the fact.

Obviously most people won't hit the cancel button here, but we did it just playing around and discovered this.

First of all, sorry my poor English. Recently my customer bought two Windows Server 2016 Standard and I have a general group policy to disable autoplay and autorun in all computers in this network. Of course, I have an Active Directory implemented with two DCs, one with W2K8R2 and another with W2K12R2. I´ve downloaded the new ADMX files for Windows Server 2016 and Windows 10 "www.microsoft.com/en-us/download/details.aspx?id=53430&quot; and created a Central Store and I made all steps recomended by Microsoft. This Group Policy works well in all versions of Windows 2012/8.1 and below, but doesn´t work in Windows version 2016/10. I reaserched in the Internet for a similiar problem and I didn´t find anything about this. Does anybody have a clue for this problem??? Thanks for any help.