Guinea Pigs on the Current Channel

M365 users during an update (image source: wikipedia)

In early June 2026 a bug in the Beta channel and in the Current Channel (Preview) of M365 caused Access applications to run extremely slowly. It only occurred in these two "Insider" channels, dedicated to test new features and find and fix bugs before they reach the standard update channels. The bug was discussed in several forums, e.g.

TechCommunity: Access VBA performance dramatically slowed since June Update

Q&A: Microsoft 365 Access running very slow the past 2 days.

AWF: Access 365 very slow

We reported it to the Microsoft Access team, and a fix for both channels was created quickly. The last affected version in the Preview channel was 2606, build 20131.20044 from June 12. The bugfix was released with the next build 20131.20052 on June 15. We informed the affected people, they updated and were delighted.

One of the forum posts informing about the fix.

All clear! ...or almost... Multiple new reports surfaced in the discussions, on the lines of:

We are on Current Channel, version 2606, build 20131.20044, and this bug is preventing us from working. When we request an update, we get the message that we are up to date.

I explained to them that this was a Preview build number, not one in the Current Channel, which was still on version 2605, that they should update to the fix or switch channels or ... Nothing worked for them.

It was not the first time we had heard such accounts of Preview builds in the Current Channel with bugs or features people shouldn't have there. But it would be the last time we suspected them of incorrect information or Microsoft of accidental channel mix-up, because when we checked with Microsoft again, we finally learned the bitter truth:

Microsoft sends Preview channel builds also to part of the user base in the Current Channel in order to test them more extensively. This Microsoft article lists the Current Channel among the Update channels subject to experimentation. The paragraph Production release build candidate validation mentions that preview builds are sent to the Current Channel for further testing.

As we've seen again in the recent example, this not only causes confusion regarding channels, versions and builds, but it also can make it difficult for those affected to find a solution. Some had to wait for another fixing update, even though the bug had already been fixed in the "correct" channel 10 days earlier.

Release note for the build that finally fixed the bug also for Current Channel users.

The Current Channel is the default setting for new M365 installations and is therefore by far the most widely used. Microsoft classifies it as a channel for production use. Until now, no one outside of Microsoft was aware that testing is intentionally conducted in this standard channel.

Based on this new information, we will update our channel article to recommend the Monthly Enterprise Channel for production use. After the Semi-Annual Channel will be discontinued in July, the monthly channel will be the only one that is not used for experiments.