Set-MgDriveItemContent uses incorrectly formatted graph end ppoint

DEBUG: [CmdletBeginProcessing]: - Set-MgDriveItemContent begin processing with parameterSet 'Set'.
DEBUG: [Authentication]: - AuthType: 'Delegated', TokenCredentialType: 'InteractiveBrowser', ContextScope: 'CurrentUser', AppName: 'Microsoft Graph Command Line Tools'.
DEBUG: [Authentication]: - Scopes: [AccessReview.Read.All, AccessReview.ReadWrite.All, AccessReview.ReadWrite.Membership, Application.Read.All, Application.ReadWrite.All, AppRoleAssignment.ReadWrite.All, AuditLog.Read.All, AuditLogsQuery.Read.All, Bookings.Read.All, ChannelMessage.ReadWrite, ChannelSettings.Read.All, DelegatedPermissionGrant.Read.All, DelegatedPermissionGrant.ReadWrite.All, Device.Read.All, DeviceManagementManagedDevices.Read.All, Directory.Read.All, Directory.ReadWrite.All, email, ExternalItem.Read.All, Files.Read, Group.Read.All, Group.ReadWrite.All, GroupMember.Read.All, IdentityRiskEvent.Read.All, OnPremDirectorySynchronization.Read.All, openid, Organization.Read.All, Policy.Read.All, Policy.ReadWrite.ApplicationConfiguration, PrivilegedAccess.Read.AzureAD, PrivilegedAccess.Read.AzureADGroup, PrivilegedAssignmentSchedule.Read.AzureADGroup, PrivilegedEligibilitySchedule.Read.AzureADGroup, profile, RoleManagement.Read.Directory, RoleManagement.ReadWrite.Directory, Sites.FullControl.All, Team.ReadBasic.All, TeamMember.Read.All, TeamworkDevice.Read.All, TeamworkTag.ReadWrite, User.Read, User.Read.All, User.ReadBasic.All, User.ReadWrite.All, UserAuthenticationMethod.Read.All].
DEBUG: Content type text/plain
DEBUG: ============================ HTTP REQUEST ============================

HTTP Method:
PUT

Absolute Uri:
https://graph.microsoft.com/v1.0/drives/b%21kA4oNtZbvEKpPLsSjEJ7S4dfN9wGhCpAhUgEYHvSBfKhADBMk4wiQ519UTHUsHC6/items/root%3A%2Fresults-55.txt/content

Headers:
FeatureFlag : 00000003
Cache-Control : no-store, no-cache
User-Agent : Mozilla/5.0,(Windows NT 10.0; Microsoft Windows 10.0.26100; en-US),PowerShell/7.6.5
SdkVersion : graph-powershell/2.39.0
client-request-id : 30e376a5-b08b-4c52-93df-524861239763
Accept-Encoding : gzip,deflate

Body:
This is a test upload file created at 09/14/2026 18:04:57
105
Mark was here.

DEBUG: ============================ HTTP RESPONSE ============================

Status Code:
BadRequest

Headers:
Transfer-Encoding : chunked
Vary : Accept-Encoding
Strict-Transport-Security : max-age=31536000
request-id : fa1da99e-e33b-43f5-bdb7-ca5b83de0399
client-request-id : 30e376a5-b08b-4c52-93df-524861239763
x-ms-ags-diagnostic : {"ServerInfo":{"DataCenter":"Central US","Slice":"E","Ring":"4","ScaleUnit":"004","RoleInstance":"DS2PEPF00003844"}}
Date : Tue, 15 Sep 2026 14:29:54 GMT

Body:
{
"error": {
"code": "BadRequest",
"message": "Entity only allows writes with a JSON Content-Type header.",
"innerError": {
"date": "2026-09-15T14:29:55",
"request-id": "fa1da99e-e33b-43f5-bdb7-ca5b83de0399",
"client-request-id": "30e376a5-b08b-4c52-93df-524861239763"
}
}
}

</details>


### Configuration

Windows 11 x64

$PSVersionTable

Name Value

PSVersion 7.6.5
PSEdition Core
GitCommitId 7.6.5
OS Microsoft Windows 10.0.26100
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.4
SerializationVersion 1.1.0.1
WSManStackVersion 3.0

### Other information

_No response_