Some Task Servers are unable to register to themselves.

The agent log shows entries like these:

Entry 1:
The unlocking of IIS configuration settings using the application
"C:\Windows\system32\inetsrv\appcmd.exe unlock config -section:system.webServer/handlers" has been succeeded.Application output:
Unlocked section "system.webServer/handlers" at configuration path "MACHINE/WEBROOT/APPHOST".
 

Entry 2:
Failed to perform re-register.
Read storage failure. Error 2 

Entry 3:
Client Task Server failed to complete registration. Will be retried in 120 seconds. Read storage failure. Error 2 

Entry 4:
The unlocking of IIS configuration settings using the application
"C:\Windows\system32\inetsrv\appcmd.exe unlock config -section:system.webServer/handlers" has been succeeded.

Application output:
Unlocked section "system.webServer/handlers" at configuration path "MACHINE/WEBROOT/APPHOST".
-----------------------------------------------------------------------------------------------------
Date: 6/8/2018 11:12:50 AM, Tick Count: 1655362052 (19.03:49:22.0520000), Size: 586 B
Process: AtrsHost.exe (5140), Thread ID: 9732, Module: AtrsHost.exe
Priority: 4, Source: Altiris.TaskManagement.Common.IISHelper.EnsureWebConfigSectionHandlersUnlocked

Entry 5:
Failed to perform re-register.
Read storage failure. Error 2
   [System.Runtime.InteropServices.COMException @ Altiris.TaskManagement.Common]
   at Symantec.NSAgent.AgentStorage.ReadItem(String pwszItemPath, UInt32 flags)
   at Symantec.NSAgent.AgentStorage.ReadItemStr(String pwszItemPath, UInt32 flags)
   at Altiris.ClientTask.Server.Communication.NotificationServerWebConnection.FigureOutCredentials()
   at Altiris.ClientTask.Server.Communication.NotificationServerWebConnection.Initialize()
   at Altiris.ClientTask.Server.ClientTaskServer.RegisterTaskServer(Version taskServerVersion)
   at Altiris.ClientTask.Server.ClientTaskServer.ReRegister(Version taskServerVersion)

COM Exception errcode: 0x2

Exception logged from:
   at Altiris.DotNetLib.Logging.AtrsLog.ExceptionMessage(String message,Exception exception)
   at Altiris.ClientTask.Server.Logging.NSAgentLog.ReportMessage(Severity severity, String moduleName, String source, Exception exception, String message, Object[] arguments)
   at Altiris.ClientTask.Server.ClientTaskServer.ReRegister(Version taskServerVersion)
   at Altiris.ClientTask.Server.ClientTaskServer.ProcessRegistrationThreadProc()
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext,ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext,ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()
-----------------------------------------------------------------------------------------------------
Date: 6/8/2018 11:12:50 AM, Tick Count: 1655362067 (19.03:49:22.0670000), Size: 1.88 KB
Process: AtrsHost.exe (5140), Thread ID: 9732, Module: AtrsHost.exe
Priority: 1, Source: Altiris.ClientTask.Server.ClientTaskServer.ReRegister

Entry 6:
Client Task Server failed to complete registration. Will be retried in 120 seconds.
Read storage failure. Error 2
   [System.Runtime.InteropServices.COMException @ Altiris.TaskManagement.Common]
   at Symantec.NSAgent.AgentStorage.ReadItem(String pwszItemPath, UInt32 flags)
   at Symantec.NSAgent.AgentStorage.ReadItemStr(String pwszItemPath, UInt32 flags)
   at Altiris.ClientTask.Server.Communication.NotificationServerWebConnection.FigureOutCredentials()
   at Altiris.ClientTask.Server.Communication.NotificationServerWebConnection.Initialize()
   at Altiris.ClientTask.Server.ClientTaskServer.RegisterTaskServer(Version taskServerVersion)
   at Altiris.ClientTask.Server.ClientTaskServer.ReRegister(Version taskServerVersion)
   at Altiris.ClientTask.Server.ClientTaskServer.ProcessRegistrationThreadProc()

COM Exception errcode: 0x2

Exception logged from:
   at Altiris.DotNetLib.Logging.AtrsLog.ExceptionMessage(String message, Exception exception)
   at Altiris.ClientTask.Server.Logging.NSAgentLog.ReportMessage(Severity severity, String moduleName, String source, Exception exception, String message, Object[] arguments)
   at Altiris.ClientTask.Server.ClientTaskServer.ProcessRegistrationThreadProc()
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()
-----------------------------------------------------------------------------------------------------
Date: 6/8/2018 11:12:50 AM, Tick Count: 1655362067 (19.03:49:22.0670000), Size: 1.89 KB
Process: AtrsHost.exe (5140), Thread ID: 9732, Module: AtrsHost.exe
Priority: 1, Source: ClientTaskServer

ITMS 8.x

The Client Policy XML (under ...\Program Files\Altiris\Altiris Agent\Client Policies) was missing the node below:

<PkgAccessCredentials UserName="aexs://AgentCore\Policy\{142F2371-E64D-43C0-A207-17DB2C0552C4}\{122439A1-8F32-4E50-AEFC-C5F4A0C47DDA}" UserPassword="aexs://AgentCore\Policy\{142F2371-E64D-43C0-A207-17DB2C0552C4}\{4CF6C037-9A8E-4D9E-8524-2018FD255209}"/>

Note: The GUIDs will be different.

These Task Servers didn't have an active "Targeted Agent settings" policy.

Check that these affected machines belongs to a "Targeted Agent settings" policy (under Settings>All Settings>Agent/Plug-ins/Symantec Management Agent>Settings. Make sure that it is not set to OFF.

Then check that the client policy xml on those machines now has a <PkgAccessCredentials> section populated.