Live streaming took a hit in mid‑August 2025 when Microsoft’s cumulative update KB5063878 for Windows 11 24H2 (and its Windows 10 counterparts) introduced a crippling regression for broadcasters. The culprit? A change in how Windows handles network transport that broke NDI’s Reliable UDP protocol, the backbone of many multi‑PC streaming rigs. Creators on Twitch and YouTube suddenly faced stuttering video, dropped frames, and audio drifting out of sync—right when they went live. Microsoft has acknowledged the issue and pointed users to vendor‑provided workarounds, while a permanent fix remains in the works.

What Went Wrong with the August Update

The update at the center of the storm, KB5063878, landed on August 12, 2025, raising Windows 11 24H2 to build 26100.4946. Companion rollups arrived for Windows 10 22H2 and 21H2. The package was a standard security and servicing release, but it silently altered low‑level networking behavior that proved disastrous for NDI (Network Device Interface).

NDI is the video‑over‑IP technology that lets one PC send pristine, low‑latency video to another over a local network. Multi‑PC streamers use it daily: the gaming rig captures gameplay and sends the feed to a dedicated encoding machine that handles the stream to Twitch or YouTube. NDI has several transport modes, with Reliable UDP (RUDP) as the modern default. RUDP adds sequencing, retransmission, and pacing on top of raw UDP to guarantee smooth delivery.

After KB5063878, RUDP flows went haywire. Instead of steady video, streamers saw repeating micro‑pauses, severe stuttering, and a gradual audio‑video desynchronization that got worse over time. Tests confirmed that the regression hits NDI’s RUDP transport specifically. Switching to the older UDP (Legacy) or Single TCP transport eliminated the symptoms immediately. Display capture sources seemed especially sensitive, more so than simple camera feeds. Applications like OBS Studio, Streamlabs, vMix, and any software relying on NDI for local source sharing all fell victim.

What It Means for Streamers

If you run a multi‑PC streaming setup that uses NDI, chances are high that your production quality nosedived after installing the August patches. The symptoms appear even when your network is barely busy—this isn’t a bandwidth problem, it’s a protocol breakdown. Single‑PC streamers who encode and broadcast from one machine without NDI are generally unaffected.

For content creators who depend on that second PC for encoding, the impact is immediate and severe. A wobbly stream loses viewers fast. Sponsors and audiences expect crisp, professional output, and a stuttering feed can ruin a live event. Microsoft’s acknowledgment, posted on its Release Health pages, confirms the scope: NDI workflows across Windows 10 and 11 are broken.

Additionally, the August update raised separate, though less widely seen, problems. Some users reported Windows Update install failures (error 0x80240069), unexpected UAC prompts during MSI repairs, and—on specific hardware—storage glitches when copying very large files. While these issues are under investigation, they do not affect NDI streaming directly. The streaming regression remains the most disruptive for the creator community.

How We Got Here: A Timeline of the NDI Break

NDI has been a trusted tool for years, and Microsoft’s monthly updates rarely break niche networking protocols. The August rollout, however, came with tweaks aimed at improving security and reliability that backfired on RUDP’s delicate timing.

  • August 12, 2025: KB5063878 ships for Windows 11 24H2; equivalent updates for Windows 10 arrive.
  • Mid‑August: Streamers begin reporting strange NDI behavior on forums and social media. The pattern is consistent: RUDP = stutter, TCP = smooth.
  • Late August: Microsoft adds the NDI regression to its Release Health notes, confirming the update as the cause and directing users to vendor guidance.
  • Early September: NDI Tools maintainers and Streamlabs publish explicit step‑by‑step workarounds, recommending a transport mode switch.

This rapid response limited the damage, but it exposed a recurring weakness in cumulative updates: changes at the OS network layer can shatter specialized, low‑latency applications that rely on precise timing assumptions.

The Quick Fix: Switch NDI Receive Mode Now

The single most effective short‑term solution is to change NDI’s receive mode away from RUDP on every affected machine. Here’s how to do it:

  1. Verify the update. On each PC, go to Settings → Windows Update → Update history and confirm that KB5063878 (or a Windows 10 equivalent like KB5063709) is listed. If it’s present, proceed.
  2. Install or open NDI Tools. Download the NDI Tools suite if you haven’t already. Launch Access Manager from the toolbox.
  3. Change receive mode. In Access Manager, click the Advanced tab. Under Receive Mode, change the setting from Auto (Recommended) / RUDP to Single TCP or UDP (Legacy). Click OK.
  4. Repeat on all PCs. You must apply this change on both the sending and receiving machines for it to take effect.
  5. Test before going live. Run a 10‑minute rehearsal stream to a private channel or record locally. Check lip‑sync and frame rate stability. If issues persist, try the other non‑RUDP transport.

Trade‑offs: Single TCP adds a small amount of latency compared to RUDP, but for most live productions the difference is negligible. UDP (Legacy) retains lower latency but gives up RUDP’s error‑correction features. Many streamers find TCP completely acceptable, but measure what works for your setup.

Quick Checklist for Live Shows

  • [ ] Change NDI Receive Mode on all machines to Single TCP or UDP (Legacy).
  • [ ] Use wired Gigabit Ethernet; disable Wi‑Fi on production PCs.
  • [ ] Avoid network switches with deep packet inspection that could exacerbate timing quirks.
  • [ ] Run a full dress rehearsal to confirm stability.

Rollback as last resort: Uninstalling KB5063878 will restore RUDP behavior but also removes the security fixes it provided. Microsoft strongly recommends using the configuration mitigation instead. If you absolutely must roll back, do so temporarily and plan compensating security measures.

Other Fallout from KB5063878

While the NDI regression grabbed headlines, the August update wasn’t fully clean.

  • Windows Installer / UAC changes: Security hardening caused some MSI repair operations to fail with error 1730 under standard user accounts. Microsoft provided a Known Issue Rollback for enterprise admins.
  • Update installation errors: A subset of machines using WSUS or the Update Catalog encountered error 0x80240069. Workarounds exist and Microsoft is investigating.
  • Storage warnings: Community testing flagged severe issues on certain SSDs, particularly those with Phison controllers, when handling very large file transfers. These reports are serious but not yet universally confirmed. If your production machines use affected drives, prioritize backups and avoid large copy jobs until the investigation firms up.

None of these directly impact NDI streaming, but they underscore the update’s broader roughness. Keep an eye on Microsoft’s official advisories for all three threads.

Outlook: When Will Microsoft Fix It?

Microsoft is currently engineering a permanent fix, though no firm date has been announced. Given the visibility and the existence of a solid workaround, the company may not rush an out‑of‑band release. Instead, a targeted patch could appear in the next one or two Patch Tuesday cycles. NDI vendors are also collaborating with Microsoft to ensure the fix fully restores RUDP without reintroducing other issues.

Until then, the transport switch is your friend. It’s low‑risk, preserves all security updates, and has been validated by thousands of streamers. Once an official fix lands, you can simply set Receive Mode back to Auto.

Stay informed: Bookmark the Microsoft Release Health page for your Windows version and the NDI Tools blog for updates. Flawless multi‑PC streaming will return—but for now, a quick setting change keeps your channel online and your audience happy.

Bottom line: KB5063878 dealt a harsh blow to NDI‑based streaming rigs, but creators don’t have to wait for a patch. Switching NDI to Single TCP or UDP (Legacy) restores stability immediately. Apply the workaround, test thoroughly, and get back to creating.