mdnsNSP.dll - This module is blocked from loading into the Local Security Authority

Short summary on this one as problem still exists: Since Local Security Authority (LSA) protection is on per default starting with Windows 11 24H2, this prompt will appear. Bonjour might be installed through iTunes or other third-party software (like Printix that simulates AirPrint). Only fix so far, is an uninstallation (if not needed any more). If needed, there is no solution. Also, Microsoft does not offer policies to define exclusions. Turning of LSA can't be seen as acceptable solution.

In the end, Apple needs to fix their Bonjour DLL. Currently, it is not fulfilling the requirements defined by Microsoft like "digitally signed with a Microsoft signature": Configure added LSA protection | Microsoft Learn

Thank you for the details. I think this is beyond my capabilities (and comprehension). I’ll just keep Bonjour installed and deal with the LSA warnings for now. I can hide the warnings if I get fed up with them.

This issue doesn’t seem to be impacting iTunes usability and that’s better than the Windows Store version that bricks devices during iOS updates and doesn’t allow you to restore. I’m so frustrated with this whole deal and the many hours I’ve spent and lost on this issue.

I have been having the same problems. To use GRBForHim's terminology iTunes from the MS Store also bricked my iPhone whist updating to iOS 18.2.1 and it would not let me restore my phone. After reading several online articles I uninstalled iTunes and installed the Apple Devices app. I did a forced restart on my phone which then displayed the symbol telling me to plug the phone into my computer. This I did after starting the Apple Devices app. This app fortunately picked up on the Backup on my computer created by iTunes and after selecting Update and waiting quite a while my phone was back to somewhere near where it was before the original attempted update via iTunes. Several apps required a re-registration with the provider but overall I was relieved that I did not have to rack my brains to recall all the apps I had got used to using.

However, as turingtest2 says I was not impressed by with the Apple Devices app. In particular it did not enable me re-install the many Podcasts I had already downloaded onto my computer. As I had read that the Apple Devices app and iTunes will not sit along side one another I uninstalled the former and reinstalled the latter but this time the version from Apple's website.

This enabled me put the Podcasts back on my phone but I am now getting the message from Microsoft's Program Compatibility Assistant as per the head of this thread. I will live with this for a while at least.

I have also had warnings about disk space on my computer and I have traced this to the fact that the newly installed iTunes from Apple stores the backups from my phone in a different location to iTunes from the MS Store.

I have posted this in the hope that the history of my experience may be of help to others.

Have you had any issues with iTunes after uninstalling Bonjour?

I get this same issue when I had to move to iTunes from Apple and not the Microsoft app store when it bricked my iPhone updating to iOS 18.2. I’ve been ignoring the LSA message when it comes up every 2/3 days (actually get 2 identical messages at once). It does give the option to not show the message again but I don’t check it because I’d like to know if this will get fixed and if it is okay to keep ignoring the message.

This is a user-to-user forum. No one here (with VERY limited exceptions) works for Apple If you want Apple to listen, use this link:

Product Feedback - Apple

Also see:

Security implications of Bonjour protocol for developers and administrators - Apple Support

Bonjour hasn't been updated since 2015. Apple would probably like you to install iTunes from the Microsoft Store, or use Apple Music, TV & Devices instead. (Don't, they're not a good replacement).

tt2

Also played around with Bonjour as separate installer. The current version is 3.1.0.1 from 2015 (extracted from iTunes installer). Also found: Download Bonjour Print Services for Windows v2.0.2 - Apple Support which gives you an even older version...

Updates to and reinstallation of version 3.1.0.1 do not fix the LSA warning.

My summary: Uninstall Bonjour (if not needed) or hope to get an updated version.

If mdnsnsp.dll is being blocked, you can add it back manually:

1. In Regedit, go to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
2. Find Security Packages and double-click it.
3. In the list that appears, add a new entry: mdnsnsp.dll
4. Click OK, close Regedit, and restart your PC.

Worked for me, anyway.

If mdnsnsp.dll is being blocked, you can add it back manually:

In Regedit, go to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

Find Security Packages and double-click it.

In the list that appears, add a new entry: mdnsnsp.dll

Click OK, close Regedit, and restart your PC.

Worked for me, anyway.

FWIW : here is what happened to me. I had NO current Apple products or software installed on my freshly built Windows 11 PC. Or so I thought. Got the Bonjour mdndnsp.dll blocking message as well (right after the 24H2 installatione). Turned out to be a Spotify plugin that was causing this behaviour on mine. Went to the installed apps and sure enought, somehow Bonjour was installed with Spotify? Just my 2cts if anyone (like me) was wondering what an Apple service was doing on my kit.

Yes, adding "mdnsNSP.dll" under this registry key activates Bonjour as Security Package and allows access to the Local Security Authority what removes the security warning: Restrictions around Registering and Installing a Security Package - Win32 apps | Microsoft Learn

Downside: This gives the DLL the ability to access access plaintext passwords of authenticated users. This mechanism is commonly exploited for credential theft. From my point of view, giving the "old" Bonjour DLL such high privileges creates a bad gut feeling and can be seen as security risk.

You can extract the Bonjour .msi file from an iTunes installer so you can install that component independently should you wish. See the bottom of Troubleshooting issues with iTunes for Windows updates - Apple Community for links to a number of versions of the iTunes installer and in particular the section on Missing MSI errors.

tt2

Do you use AirPlay or sync over Wi-Fi? If not then I don't think you need Bonjour at all.

tt2

uninstalled itunes and bonjour, and got itunes from the apple website instead, warning has gone and itunes now recognizes phone, so all good. GL to you.