SharePoint.Files "Token refresh timed out" since late May 2026 - fix inside

[Henri-]

Hey everyone,

Spent way too long on this so posting here in case it saves someone else the headache.

What was happening: All my Power Query queries using SharePoint.Files suddenly started failing with [Permission Error] Token refresh timed out when refreshing tables in Excel. Everything worked fine in the PQ editor. Started around May 22nd 2026, affected multiple workbooks and scripts at once, even a brand new blank workbook with the same script.

How I diagnosed it: Tested each connector one by one by actually loading to a sheet, not just previewing in the PQ editor. SharePoint.Tables loads fine. SharePoint.Contents loads fine. SharePoint.Files with ApiVersion 15 times out even just listing 10 files. SharePoint.Files with ApiVersion 14 loads but returns empty results. So the problem was specifically SharePoint.Files with ApiVersion 15 during table refresh.

The fix: Right-click your query table in Excel, go to Table, then External Data Properties, and uncheck Enable fast data load. No M code changes needed at all.

Why it works (according to Claude): Microsoft retired the legacy IDCRL auth protocol for SharePoint Online in May 2026, tightening OAuth2 token management for background sessions. Enable fast data load runs the refresh in a detached background process that cannot renew an OAuth token mid-refresh. With it disabled, the refresh runs in your foreground session and can renew tokens the same way the PQ editor does.

Hope this helps someone!

[Poojara_D12]

Hi @Henri- 

That is an incredibly sharp diagnostic catch, and thank you so much for documenting this workaround for the community! That background change by Microsoft regarding legacy authentication protocols has been causing silent token drops across a lot of tenant configurations lately. To add some extra technical weight to your explanation for anyone trying to understand why this happens: when Enable fast data load is active, Excel prioritizes raw ingestion speed by pulling data on a separate, heavily optimized thread that skips the standard user-facing authentication handshakes to save memory. Because that secondary thread operates in an isolated background container, it is completely blind to interactive OAuth2 renewal prompts; the moment the initial session token expires or requires a routine refresh mid-stream, the process instantly times out with a permission failure. Disabling fast data load forces Excel to synchronize the data pull directly inside the main application thread, allowing the underlying Power Query engine to leverage your live, foreground Windows session to seamlessly rotate and refresh the SharePoint OAuth2 tokens exactly like it does when you are working inside the Power Query Editor.