Power Query Editor freezes (Not Responding) for 20 seconds when opening even a trivial 2-row/3-column table

Question

Power Query Editor freezes (Not Responding) for 20 seconds when opening even a trivial 2-row/3-column table

oleg kaz 0

Product: Microsoft 365 Personal, Excel, Version 2608 Build 20326.20000 (Insider Beta Channel)

Description:

Power Query Editor consistently freezes and displays "Not Responding" for 20-30 seconds every time it opens, even on a brand-new, trivial workbook (3 columns, 2 rows, loaded from a simple range/table). The delay happens on the very first load and also on every subsequent load within the same Excel session — closing the editor and reopening it on the same query produces the same 20-30 second freeze each time.

This is not related to data volume: the same freeze occurs on a 246-row table and on a 2-row test table equally.

Troubleshooting already performed (no change in behavior):

Disabled all COM add-ins (including Adobe Acrobat PDFMaker, xlwings) — no effect
Tested in Excel Safe Mode (excel.exe /safe) — same 20-30 second freeze persists
Set "Always ignore Privacy Level settings" in Power Query privacy options — no effect
Confirmed memory/CPU are not the bottleneck — system has 16GB RAM (AMD Ryzen 5000 series), verified via Task Manager that memory usage is normal (~50-60%) and not the cause
Monitored Task Manager during the freeze: Microsoft.Mashup.Container.Loader.exe shows 0% CPU / near-0 memory (idle, not computing), while EXCEL.EXE itself shows active CPU usage and growing working set during the freeze — indicating the hang is inside the Excel UI thread itself, not an external wait
Disabled Windows Defender real-time protection entirely and retested — no effect
Confirmed "Not Responding" state appears both on the Power Query Editor window and, separately, on the initial "Queries & Connections" pane (~6-7 seconds), though the pane only hangs on first use per session while the Editor hangs every time
Checked and found no "Disable hardware graphics acceleration" option available under Excel Options → Advanced on this build

Expected behavior: Power Query Editor should open near-instantly for a dataset this small, consistent with behavior on other machines/installations.

Actual behavior: 20-30 second freeze with "Not Responding" on every single Power Query Editor open, regardless of data size or session state.

Suspected cause: Given that add-ins, antivirus, and memory have all been ruled out, and the freeze is reproducible even on a brand-new empty workbook, this appears to be either a regression specific to Insider Beta Channel Build 20326.20000, or a corrupted Mashup engine component registration requiring reinstall/repair.

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Answer 1

oleg kaz 0

I applied this solution, but it had no impact on the Power Query launch speed. Even after disabling "Enable background refresh" and renaming the folder to PowerQuery.old, the opening speed remains exactly the same both with and without background refresh active. Regarding the second suggestion (switching from the Beta/Dev channel to the Current channel) — I prefer not to switch and would like to stay on my current update channel for now.

Kai-H 26,385 Reputation points Microsoft External Staff Moderator

2026-08-10T06:18:17.5433333+00:00

Hi, oleg kaz

Thank you for confirming the results. Since background refresh and the Power Query cache have no effect, the delay is occurring before query evaluation, most likely while Excel initializes the Power Query interface or .NET components.

If you prefer to remain on the Beta/Dev channels, no channel change is required. The most useful next test is temporarily rolling Office back to the previous Beta Channel build, while keeping the same channel. Microsoft supports reverting Click-to-Run Office to an earlier build when an update introduces unexpected behavior.

If the previous Beta build opens Power Query normally, that provides strong evidence of a regression in Build 20326.20000. Disable Office updates temporarily after rolling back so the affected build is not immediately reinstalled, then re-enable updates when a newer Beta build becomes available.

Answer 2

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Answer 3

oleg kaz 0

Disabling Enable background refresh in the Query Properties improved the Power Query editor opening speed to ~5 seconds, but the initial 8-9 second cold-start delay for the 'Queries & Connections' task pane itself persists.

Severe 8-9 second delay during .NET Framework initialization when opening "Queries & Connections" pane in Excel (Windows 11 Dev Channel)
Description:Environment:OS: Windows 11 Pro (Dev Channel, latest flight)
Hardware: High-speed NVMe SSD, modern CPU
Summary:There is a consistent 8 to 9-second delay/freeze (accompanied by the blue loading spinner and the "Loading .NET Framework" status message at the bottom) when clicking the "Queries & Connections" button under the Data tab in Excel.
This issue occurs only during the very first (cold) initialization of the pane in an Excel session. Subsequent openings of the pane are instant. However, this delay is highly disruptive and reproduces even on a completely blank, newly created workbook.
Diagnostic Steps Already Taken (None of these resolved the issue):

Network Disconnected: Disabling Wi-Fi/Internet completely does not change the timing. The delay remains exactly 8-9 seconds, ruling out a network-based CRL (Certificate Revocation List) timeout.
Exploit Protection (SimExec / Child Processes): Configured Exploit Protection overrides for excel.exe (disabling SimExec and Child Process mitigation).
All Excel COM Add-ins have been disabled, global Power Query caches cleared, and custom XML data inspected/removed. Microsoft .NET Framework Repair Tool was also deployed.
Office Repair: Performed a full online repair/reinstallation of Microsoft 365.

Kai-H 26,385 Reputation points Microsoft External Staff Moderator

2026-08-05T06:31:13.5466667+00:00

Hi, oleg kaz

The improvement from disabling background refresh separates the Power Query Editor delay from the remaining pane delay. Since “Loading .NET Framework” occurs once per Excel session, even with a blank workbook, this now looks more like cold initialization in the Insider environment than a query, cache, or network problem.

Test Excel Current Channel on a stable, non-Insider Windows 11 installation, or another PC using the same Microsoft 365 account. A similar “Loading .NET Framework” issue stopped after the Insider Office installation was replaced with the regular Microsoft 365 release.

If only this Windows Dev Channel device is affected, avoid further registry or Exploit Protection changes. They have not improved the delay and may complicate diagnosis.

Record a short screen video showing the first and second pane openings, then submit feedback through Excel > Help > Feedback > Report a Problem and Feedback Hub > Apps > Microsoft 365. Include the exact Office and Windows build numbers and attach a trace recorded while reproducing the first opening.

At this stage, another Office or .NET repair is unlikely to add useful information. The most valuable test is stable Windows plus Current Channel Office.
oleg kaz 0 Reputation points

2026-08-06T07:37:56.4433333+00:00

I truly appreciate your advice.

Answer 4

Hi, oleg kaz

Since the delay also occurs in Safe Mode with a new workbook, it is unlikely to be caused by the data, add-ins, or antivirus. Build 20326.20000 was released to the Beta Channel on July 29, 2026, but this specific behavior is not listed as a confirmed known issue.

Here are some suggestions you can try:

Close all Office applications. Open %LocalAppData%\Microsoft\Office\16.0 and rename the PowerQuery folder to PowerQuery.old, then restart Windows. Excel will recreate the Power Query cache. This has resolved similar cases where the editor froze even with blank workbooks.

Temporarily leave the Beta Channel and switch to Current Channel. Then open Excel, select File > Account > Update Options > Update Now, and retest. If the delay disappears, that strongly points to a Beta-build regression rather than a damaged workbook.

If it continues on Current Channel, open Windows Settings > Apps > Installed apps > Microsoft 365 > Modify, then run Online Repair, not Quick Repair. Online Repair replaces the full Office installation and damaged components.

Finally, submit the issue through Excel > Help > Feedback > Report a Problem, including the build number and the fact that switching channels changes the behavior, if confirmed.

Thank you for your patience in reading, I hope this information has been helpful to you.

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