Powershell: Get-StoredCredential not working when script is run from task scheduler

I am writing a powershell script which shall periodically run to backup the contents of a remote folder. That remote folder is mapped as a WebDav share to my Windows drive G:\.

This post and this one say

• that mapped drives cannot be accessed directly and
• that they should be accessed via UNC.

Accessing the remote folder via UNC requires that I provide credentials. I don't want them lying around in plain text, so I try to access them via the Credentials Manager. I have thus done the installation of module CredentialManager, and now, getting the credentials and mounting the remote folder

• works fine if I run the script manually (from within MS Code)
  • my powershell version is 7.3.6
• fails if the script is run from the task scheduler though
  • the user is the same (see output of whoami), it is a non-admin account
  • the user has the "Logon as batch job" rights
  • run with highest privileges is not ticked
  • I tried both, Run whether user is logged on or not and Run only when user is logged on, but it makes no difference

Why is that and what can I do to get access to the remote folder from the scheduled script?

The script access.ps1:

# MAIN ######################################################################## $debuglog = $PSScriptRoot + "\" + "debuglog.txt" #$debuglog = $null $PSDefaultParameterValues = @{'Out-File:Encoding' = 'utf8'} # https://stackoverflow.com/questions/64757125/how-to-specify-file-format-for-powershell-tee-command # https://stackoverflow.com/questions/40098771/changing-powershells-default-output-encoding-to-utf-8 # https://stackoverflow.com/questions/30606929/tee-with-utf-8-encoding # Info: echo "$(get-date -format 'yyMMdd-HHmmss') ##################################################" >> $debuglog echo "Which domain/account?: <$(whoami)>" >> $debuglog echo "Available drives:" $(get-psdrive) >> $debuglog # OK, when drive does not show up when script is run from task scheduler, then let's map it: $credential = Get-StoredCredential -Target "webdav.mc.gmx.net" echo "Credential: _$credential_" >> $debuglog if ($credential) { echo "Credentials found." >> $debuglog $username = $credential.UserName $password = $credential.GetNetworkCredential().Password $driveLetter = "Y" $networkPath = "\\webdav.mc.gmx.net@SSL\DavWWWRoot\myData\" remove-psdrive $driveLetter New-PSDrive -Name $driveLetter -PSProvider FileSystem -Root $networkPath -Credential $credential } else { echo "Accessing credentials failed." >> $debuglog } echo "psdrives:" $(get-psdrive) >> $debuglog echo "Dir: " $(dir y:\) >> $debuglog remove-psdrive $driveLetter echo "Exit." >> $debuglog exit 

The output of the script:

• left: when run "manually", i.e. from MS Code
• right: when run through the task scheduler
  • user names are identical
  • drive G:\ is not available
  • accessing credentials failed

The scheduler's XML:

<?xml version="1.0" encoding="UTF-16"?> <Task version="1.4" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task"> <RegistrationInfo> <Date>2023-07-31T23:41:50.6178473</Date> <Author>DELFIN7\Martin</Author> <URI>\Access2</URI> </RegistrationInfo> <Triggers> <CalendarTrigger> <StartBoundary>2023-07-31T23:40:09</StartBoundary> <Enabled>true</Enabled> <ScheduleByMonth> <DaysOfMonth> <Day>13</Day> </DaysOfMonth> <Months> <January /> <February /> <March /> <April /> <May /> <June /> <July /> <August /> <September /> <October /> <November /> <December /> </Months> </ScheduleByMonth> </CalendarTrigger> </Triggers> <Principals> <Principal id="Author"> <UserId>S-1-5-21-48XXXXX20-12XXXXXX13-21XXXXXX82-1001</UserId> <LogonType>Password</LogonType> <RunLevel>LeastPrivilege</RunLevel> </Principal> </Principals> <Settings> <MultipleInstancesPolicy>Parallel</MultipleInstancesPolicy> <DisallowStartIfOnBatteries>false</DisallowStartIfOnBatteries> <StopIfGoingOnBatteries>false</StopIfGoingOnBatteries> <AllowHardTerminate>true</AllowHardTerminate> <StartWhenAvailable>true</StartWhenAvailable> <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable> <IdleSettings> <StopOnIdleEnd>true</StopOnIdleEnd> <RestartOnIdle>false</RestartOnIdle> </IdleSettings> <AllowStartOnDemand>true</AllowStartOnDemand> <Enabled>true</Enabled> <Hidden>false</Hidden> <RunOnlyIfIdle>false</RunOnlyIfIdle> <DisallowStartOnRemoteAppSession>false</DisallowStartOnRemoteAppSession> <UseUnifiedSchedulingEngine>true</UseUnifiedSchedulingEngine> <WakeToRun>false</WakeToRun> <ExecutionTimeLimit>PT0S</ExecutionTimeLimit> <Priority>7</Priority> <RestartOnFailure> <Interval>PT2H</Interval> <Count>120</Count> </RestartOnFailure> </Settings> <Actions Context="Author"> <Exec> <Command>C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe</Command> <Arguments>"D:\Datenbanken\Datensicherung\myRoboBak\Executables\access.ps1"</Arguments> <WorkingDirectory>D:\Datenbanken\Datensicherung\myRoboBak\Executables\</WorkingDirectory> </Exec> </Actions> </Task>