I am unable to Edit aspx pages in Sharepoint Designer 2013

Hi Arun Palani

Thank you for reaching out to Microsoft Q&A forum support and apologize for the inconvenience

I have conducted some research and found that SharePoint Designer 2013 is considered deprecated. However, deprecation does not necessarily mean it stops working immediately. Microsoft’s lifecycle information shows SPD 2013 remains in extended support until July 14, 2026, as states in LINK.

Regarding the specific behavior you’re seeing (“Method not supported” / “Specified method is not supported”), this aligns with a current temporary problem impacting SharePoint Online where users are unable to edit SharePoint Online sites using SPD 2013 and receive this type of “method not supported” SOAP/server error. We are acknowledged this and it's being actively investigated.

In the meantime, you can try some workarounds below to see if it can temporarily help you:

1. Use the supported browser editing experience if your goal is to edit pages, use SharePoint’s built-in page editing in the browser (this is the supported path and avoids dependency on SPD). Microsoft provides guidance for creating and editing classic SharePoint pages via the SharePoint UI.
2. Try common SharePoint Designer client-side remediation:
   • Update SharePoint Designer 2013 to the latest available updates.
   • Clear saved Windows credentials (Credential Manager) and sign in again.
   • Clear SharePoint Designer cache folders and retry (cache corruption can trigger unexpected behavior).

Hope my answer will help you and if I have any update about this, I am going to inform you as soon as possible

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SharePoint Designer 2013 itself is not yet removed, but it is deprecated and has limited future support.

From the provided information:

• SharePoint Designer 2013 is explicitly listed as deprecated for SharePoint Server Subscription Edition and will remain supported only until July 14, 2026. After that date it will no longer be supported.
• Deprecated means no new investments or enhancements are made, and the feature may be removed in future updates. Organizations are encouraged to move away from it.

So:

• Yes, SharePoint Designer 2013 is deprecated as a product/feature.
• However, deprecation alone does not immediately block page editing; the new "Method not supported" error is more likely due to changes in the SharePoint environment (for example, configuration or platform updates) rather than the product suddenly being removed.
• For page customization going forward, the guidance is to avoid new dependencies on SharePoint Designer and to use built‑in page editing in SharePoint, and other supported customization options instead.

Also note:

• SharePoint no longer contains a built‑in HTML editor; page editing is done through the SharePoint UI. For deeper customization, SharePoint Designer has historically been used, but it is now deprecated.

If continued editing via SharePoint Designer is required in the short term, coordinate with the SharePoint administrator to confirm:

1. The site is still configured to allow editing with SharePoint Designer.
2. No recent upgrade or policy change has disabled or restricted Designer editing.

Longer term, plan to migrate away from SharePoint Designer 2013 before its support end date.

References:

• What's deprecated or removed from SharePoint Server Subscription Edition
• Are you looking for Edit a page by using the HTML Editor?