Maester failing with this error since mid June 2025

[sanalpr]

Our Maester Azure Pipelines deployed implementation is failing with the below error:
I have tried getting the latest, re-install etc. Can someone please help point to where the issue could be?

##[error] System.Management.Automation.RuntimeException: Invoking step End failed:
##[error] Result 1 - Error 1:Export-XmlReport : Exception calling "WriteElementString" with "2" argument(s): "'.', hexadecimal value 0x00, is an invalid character."
##[error] At C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1:18012 char:13
##[error] + Export-XmlReport -Result $Result -Path $Path -Format $For …
##[error] + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
##[error] + CategoryInfo : NotSpecified: (:) [Export-XmlReport], MethodInvocationException
##[error] + FullyQualifiedErrorId : ArgumentException,Export-XmlReport
##[error] at Write-NUnitTestCaseAttributes, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 17271
##[error] at Write-NUnitTestCaseElement, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 17165
##[error] at Write-NUnitTestSuiteElements, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 17037
##[error] at Write-NUnitTestSuiteElements, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 17009
##[error] at Write-NUnitTestResultChildNodes, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 16957
##[error] at Write-NUnitReport, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 16911
##[error] at Export-XmlReport, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 18156
##[error] at Export-PesterResult, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 18012
##[error] at , C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 18501
##[error] at Invoke-PluginStep, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 1800
##[error] at Invoke-Pester, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 4991
##[error] at Invoke-Maester, C:\Users\adminuser\Documents\PowerShell\Modules\Maester\1.3.0\public\Invoke-Maester.ps1: line 377
##[error] at , C:\agent_work_temp\b82b9bc3-d911-4a97-9565-6748f5f7ad1c.ps1: line 39
##[error] at , : line 1
##[error]
##[error] at Assert-Success, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 1857
##[error] at Invoke-PluginStep, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 1819
##[error] at Invoke-Pester, C:\Users\adminuser\Documents\PowerShell\Modules\Pester\5.7.1\Pester.psm1: line 4991
##[error] at Invoke-Maester, C:\Users\adminuser\Documents\PowerShell\Modules\Maester\1.3.0\public\Invoke-Maester.ps1: line 377
##[error] at , C:\agent_work_temp\b82b9bc3-d911-4a97-9565-6748f5f7ad1c.ps1: line 39
##[error] at , : line 1
Account Environment Tenant TenantId

[ri-we]

I have the same issue, but only when I connect to EXO or Teams. Any fix available?

[sanalpr]

Yes, after much troubleshooting, this turned out to be a permission issue.. I needed to create a exchange pointer( and EXO SP) for my service principal and in exchange give that SP "View-Only Organization Management" role