Printer Not Printing After the August 2026 Windows Update

Printer Not Printing After the August 2026 Windows Update? Here's the Real Fix

If your printer or PDF export suddenly stopped working this week — and you didn’t touch a single setting — you’re not losing your mind. Microsoft has officially confirmed that its August 2026 Patch Tuesday update broke printing in a range of Windows applications, and thousands of home and business users are running into it right now.

Here’s exactly what’s happening, why it’s hitting so many printers at once, and what you can do about it today — including the safest fix if you’d rather not touch technical settings yourself.

What’s Actually Going Wrong

Microsoft has confirmed that the .NET Framework updates released with the August 2026 Patch Tuesday are causing printing and PDF export failures in applications built on Windows Presentation Foundation (WPF) — a framework used by a large number of everyday Windows programs, including many invoicing tools, PDF viewers, accounting apps, and custom business software.

Affected apps can throw a System.IO.FileFormatException the moment you try to print or export a PDF, especially when the document uses certain fonts such as Calibri. Instead of printing your document, the app simply fails.

This isn’t a one-off glitch tied to a single printer brand. It’s a system-level change that can affect Windows 10, Windows 11, and Windows Server (including Server versions from 2012 through 2025), which is why it’s spreading across so many households and offices at once.

Why This Feels Different From a Normal “Printer Offline” Error

Printer Not Printing After the August 2026 Windows Update

Most printer problems come from a driver conflict, a lost network connection, or a print spooler crash — and those are usually fixable in a few minutes on your end. This one is different because:

  • It comes from a Windows system update, not your printer or router
  • It doesn’t only affect one printer brand — HP, Canon, Epson, Brother, and others can all be impacted if the app you’re printing from uses WPF
  • The failure often shows up as a software error message, not a simple “offline” status
  • Microsoft has not released a permanent fix yet — only a temporary workaround

If you’ve already tried the usual steps — restarting the printer, checking cables, reinstalling drivers — and nothing changes, this update is very likely the real cause.Printer Not Printing After the August 2026 Windows Update

Microsoft’s Official Workaround (And Its Hidden Risk)

Microsoft has published a temporary fix: enabling a setting called the Switch.MS.Internal.TtfDelta.DisableCmapAndSbitOverflowProtection AppContext switch inside the affected application’s configuration file. This allows the app to resume printing and generating PDF/XPS files.

Here’s the catch: this switch works by turning off a security protection that was introduced by the same August 2026 .NET Framework update — a Patch Tuesday release that fixed more than 400 separate vulnerabilities. Turning the protection back off to fix printing means your system is technically exposed again to the issues that patch was designed to close. Printer Not Printing After the August 2026 Windows Update

Microsoft itself recommends using this workaround only when necessary, and removing it as soon as a permanent fix is released. For most home users and small businesses, editing application config files and weighing security trade-offs isn’t something you want to get wrong — one incorrect edit can leave a config file broken or a security gap open without you realizing it.

What You Should Do Right Now

  1. Confirm it’s actually this update. If printing or PDF export suddenly broke after installing Windows updates this month, and other basic fixes (power cycle, spooler restart, cable/Wi-Fi check) haven’t helped, this is likely the cause.
  2. Don’t uninstall your printer driver as a first step. Since the issue lives in Windows’ .NET Framework rather than your printer’s driver, removing and reinstalling drivers usually won’t fix it — and can create a second problem on top of the first.
  3. Back up before making any system-level change. If you or anyone else applies the AppContext workaround, make sure you understand exactly which application and files you’re editing.
  4. Get a second pair of eyes before disabling a security protection. This is exactly the kind of fix where a wrong move causes more damage than the original problem.

Get It Fixed the Safe Way — Without the Guesswork

This is precisely the situation our remote support team handles every day: a Windows-level change that’s affecting your ability to print, with a workaround that carries real security trade-offs if it’s applied incorrectly.

When you book a session with Printer Setup Guide, one of our technicians connects remotely and:

  • Confirms whether this update — or something else entirely — is behind your printing failure
  • Applies the correct, safest configuration only where it’s actually needed
  • Checks your printer, drivers, and Windows print settings end-to-end so nothing else is silently broken
  • Explains what changed and what to watch for once Microsoft ships a permanent fix

You don’t need to touch a single config file yourself. Book remote printer support and get back to printing today, on any major brand — HP, Canon, Epson, Brother, and more. Printer Not Printing After the August 2026 Windows Update

Frequently Asked Questions

Is my printer broken? No. In this case, the problem is a Windows system update, not a hardware fault. Your printer itself is very likely fine.

Does this only affect certain printer brands? No. Because the issue lives in Windows’ .NET Framework and affects any app built on WPF, it can appear regardless of whether you use an HP, Canon, Epson, Brother, or other printer.

Will uninstalling the Windows update fix it? Rolling back the update may resolve the symptom for some users, but it also removes the security fixes included in that update, which isn’t a safe long-term option for most people. A supported workaround or professional configuration check is a safer route.

Has Microsoft released a permanent fix? Not yet, as of this writing. Microsoft has only published a temporary workaround and says it is still investigating a full fix.

What if I’m not comfortable editing configuration files myself? That’s exactly what our remote support service is for — a technician handles it for you, safely, over a secure remote session.