Issue running Get-MgUser in v2.0.0-Preview5 - Collection was modified; enumeration operation may not execute. Possible PageSize issue in PS 5.1

[stukey]

We have an existing PowerShell reporting script that we have recently migrated from the MSOL to Graph PowerShell SDK PS module. We are seeing the script regularly fail with a generic “An error occurred while sending the request” error. We see the same error for Get-MgUser and Get-MgDevice cmdlets. The cmdlets return results, but not all results that are available in the tenant. We are using the Microsoft Graph PowerShell SDK module version 2.0.0-preview5 (and also tested in preview8). We are authenticating using App Only authentication via custom AAD app Client Id and Client Secret (hence why we are using v2.00 rather than v1). We’re running under PowerShell 5.1. I believe the error could be related to PageSize since we have over 140,000 users and 200,000+ devices in our tenant. This seems similar to a previously reported issue: #1192, which was supposed to be fixed.

I've confirmed that setting the PageSize to 500 avoids the error in both the Get-MgUser and Get-MgDevice cmdlets.

Example code:

[array]$tmpUsers = Get-MgUser -All -Property City, Country, Department, OnPremisesProvisioningErrors, DisplayName, GivenName, OnPremisesImmutableId, OnPremisesLastSyncDateTime, Surname, LastPasswordChangeDateTime, AssignedLicenses, LicenseAssignmentStates, MobilePhone, Id, OfficeLocation, ProvisionedPlans, BusinessPhones, PostalCode, UsageLocation, DeletedDateTime, State, StreetAddress, SignInSessionsValidFromDateTime, JobTitle, UserPrincipalName, UserType, CreatedDateTime
 
Get-MgUser : An error occurred while sending the request.
 
At line:1 char:1
+ [array]$tmpUsers = Get-MgUser -All -Property City, Country, Departmen ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Get-MgUser_List], HttpRequestException
    + FullyQualifiedErrorId : Microsoft.Graph.PowerShell.Cmdlets.GetMgUser_List
 
$error | FL -Force
 
writeErrorStream      : True
Exception             : System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
                           at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
                           at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext()
                           at System.Net.Http.Headers.HttpHeaders.<GetEnumerator>d__20.MoveNext()
                           at System.Net.Http.Headers.HttpHeaders.ToString()
                           at System.Net.Http.WinHttpHandler.AddRequestHeaders(SafeWinHttpHandle requestHandle, HttpRequestMessage requestMessage, CookieContainer cookies,
                        DecompressionMethods manuallyProcessedDecompressionMethods)
                           at System.Net.Http.WinHttpHandler.<StartRequestAsync>d__122.MoveNext()
                           --- End of inner exception stack trace ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
                           at Microsoft.Graph.RedirectHandler.<SendAsync>d__6.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
                           at Microsoft.Graph.RetryHandler.<SendAsync>d__9.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
                           at Microsoft.Graph.CompressionHandler.<SendAsync>d__2.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
                           at Microsoft.Graph.AuthenticationHandler.<SendAsync>d__16.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
                           at Microsoft.Graph.PowerShell.Users.<UsersUserListUser_Call>d__377.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at Microsoft.Graph.PowerShell.Users.<UsersUserListUser_Call>d__377.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at Microsoft.Graph.PowerShell.Cmdlets.GetMgUser_List.<on2Xx>d__86.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
                           at Microsoft.Graph.PowerShell.Users.<UsersUserListUser_Call>d__377.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at Microsoft.Graph.PowerShell.Users.<UsersUserListUser_Call>d__377.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
                           at Microsoft.Graph.PowerShell.Users.<UsersUserListUser>d__375.MoveNext()
                        --- End of stack trace from previous location where exception was thrown ---
                           at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
                           at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
                           at Microsoft.Graph.PowerShell.Cmdlets.GetMgUser_List.<ProcessRecordAsync>d__84.MoveNext()
TargetObject          :
CategoryInfo          : NotSpecified: (:) [Get-MgUser_List], HttpRequestException
FullyQualifiedErrorId : Microsoft.Graph.PowerShell.Cmdlets.GetMgUser_List
ErrorDetails          :
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at Get-MgUser<Process>, C:\Program Files\WindowsPowerShell\Modules\Microsoft.Graph.Users\2.0.0\exports\ProxyCmdletDefinitions.ps1: line 5854
                        at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo : {0, 1}
PSMessageDetails      :

[SeniorConsulting]

Thanks for documenting this.

Hmm. I've had this issue on single user write methods before too, so I'm not sure whether setting page size is the fix (though I'll definitely investigate this in my scripts/environment):

• Update-MgUser
• Get-MgServicePrincipal
• Get-MgApplication

And others

I think peombwa is aware of this already, over in #1872

[peombwa]

Thanks for bringing this to our attention and the detailed logs!

We will investigate and provide a fix in v2. As a workaround, you can consider using PowerShell 7 since the issue is isolated to PowerShell 5.1.

[CarolKigoonya]

Hello @SeniorConsulting, my name is Carol, the new MS Graph PowerShell PM. We have identified you as one of the recipients of an early adopter program. Please share your email address with me so that we can send the badge to you.

[peombwa]

Thanks for your patience as we investigated the issue.

I've traced the root cause to how request headers are handled in the underlaying WinHttpHandler. In v2, the Microsoft Graph .NET Core SDK defaults to WinHttpHandler as its final HTTP handler when running on .NET Fx (PowerShell 5.1). The bug will be fixed by #2028.

[stukey]

Thanks for the update @peombwa.