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SharePoint Designer shows the error: The server could not complete your request.

Cemil Chamma 20 Reputation points
2026-04-18T06:27:59.3266667+00:00

We've got server-side error in SharePoint Server when attempting to access Page Layouts WelcomeLinks.aspx from SharePoint Designer.

When clicking or opening a page layout, SharePoint Designer shows the error: The server could not complete your request.

Clicking Details displays the following message:

Module: ManagedPipelineHandler
Notification: ExecuteRequestHandler
Handler: ScriptHandlerFactory
Error Code: 0x00000000
Requested URL: http://<site>/_vti_bin/webpartpages.asmx
Physical Path: C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\isapi\webpartpages.asmx
Logon Method: Federated Logon
Logon User: <User>

TIY, have a nice weekend

Microsoft 365 and Office | SharePoint Server | For business
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  2. Steven-N 25,305 Reputation points Microsoft External Staff Moderator
    2026-04-18T07:07:34.3766667+00:00

    Hi Cemil Chamma

    From the error logs you sent, I can see that Logon Method: Federated Logon is the primary cause of this concern.

    As far as I know, SharePoint Designer communicates with the farm via _vti_bin/webpartpages.asmx using classic/Windows (NTLM/Kerberos) authentication internally, so when the Web Application's authentication provider is Claims/Federated only, the _vti_bin The virtual directory may not negotiate auth correctly for SPD's service calls, causing the request to fail at the handler level, even though the Windows error code is 0x00000000 .

    That said, from my perspective, you can try 2 options below to see if it helps.

    However, first of all, before making changes, pull the ULS log from the server at the time of the failure:

    Merge-SPLogFile -Path "C:\Logs\SPD_error.log" -Overwrite -StartTime (Get-Date).AddMinutes(-10)

    Filter for webpartpages or ScriptHandlerFactory entries. The ULS correlation ID will tell you exactly where it breaks internally

    Option 1: Enable Windows authentication on the web application

    In Central Administration > Application Management > Manage Web Applications:

    1. Select the affected Web Application > Authentication Providers
    2. Click the Zone (usually Default)
    3. Under Claims Authentication Types, ensure Windows Authentication > NTLM is checked in addition to your federated provider
    4. Save and do an IISReset

    SharePoint Designer requires a Windows-negotiable auth channel to call _vti_bin services. Federated-only zones block this.

    Option 2: Check _vti_bin IIS Authentication Settings

    The _vti_bin virtual directory can get out of sync with the parent Web Application's IIS site:

    1. Open IIS Manager on the WFE
    2. Expand the site > find _vti_bin
    3. Open Authentication
    4. Ensure Windows Authentication is Enabled
    5. Ensure Anonymous Authentication is Disabled (or matches your site config)

    If Windows Authentication is missing or disabled here specifically, SPD's ASMX calls will fail with exactly this symptom even if the parent site looks fine.

    In case the issue still persists, kindly let me know in the comment section for further support

    Best regards

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  3. AI answer

    2026-04-18T06:28:06.75+00:00

    The error occurs because anonymous authentication is disabled for the SharePoint web application in IIS. When SharePoint Designer connects and calls WCF services such as webpartpages.asmx, the WCF runtime expects its security settings to match IIS. With anonymous authentication turned off, WCF cannot use anonymous binding and throws an exception, which SharePoint Designer surfaces as:

    The server could not complete your request.

    To fix the issue, enable anonymous authentication for the affected SharePoint web application in IIS.

    At a high level:

    1. Open IIS Manager on the SharePoint server.
    2. Locate the SharePoint web application that hosts the site being opened in SharePoint Designer.
    3. Select the site, open Authentication.
    4. Enable Anonymous Authentication for that web application.

    After enabling anonymous authentication, retry opening the page layout in SharePoint Designer.

    References:

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