LANMAN AUTHENTICATION MUST COME BACK. YOU ALL DID SOMETHING HORRIBLE TO THE DOS COMMUNITY.

With the release of Windows 11 version 24H2, Microsoft has fully removed NTLMv1 authentication support. This is not just a deprecation—this is a full removal of a feature that has existed and been relied on for over two decades. As a result, legacy clients such as MS-DOS 6.22 with Microsoft Network Client 3.0, Windows 95, and Windows 98 can no longer authenticate with modern Windows systems, even in isolated environments where security risks are not a factor.

This change completely breaks functionality that previously worked in Windows 10 and earlier Windows 11 versions. When attempting to connect from an MS-DOS client, I receive a “password incorrect” error followed by “Access denied: Error 5,” even though the credentials are correct and the configuration is unchanged. LM and NTLMv1 were the only supported protocols on these systems. With NTLMv1 removed, they are now completely locked out.

This is a major problem. Microsoft has, with this change, cut off all native support for retro and vintage systems from Windows-based file servers. There is no workaround provided. There is no opt-in compatibility mode. And there is no Microsoft-supported alternative. The only path forward is to install and configure a third-party Linux server running Samba, configured to accept insecure authentication. For many users, that is not a realistic or acceptable solution.

These legacy systems are not running on production networks. They are used in air-gapped labs, museums, personal collections, restoration projects, educational environments, retro software development, and digital preservation. These setups do not need modern security protocols—they need access. Until now, Microsoft had made it possible to continue supporting these systems with careful configuration. With 24H2, that path has been entirely removed.

This decision is extremely damaging to the retro computing community. It ends compatibility for a large number of legitimate, historically significant systems. It eliminates decades of backward support with no replacement. And it sends a clear message that retro computing is no longer supported by Microsoft at any level, even as an opt-in legacy feature.

Yes, NTLMv1 is insecure. Yes, it should be disabled by default. But removing it entirely, without even offering an advanced option to re-enable it, is unnecessary and harmful. Microsoft already handles other legacy protocols—like SMBv1—as optional features with warnings. NTLMv1 should be treated the same way.

I am asking Microsoft to reintroduce NTLMv1 as an optional, unsupported legacy authentication mode. This can be done safely behind a registry key, group policy, optional Windows feature, or PowerShell command. It does not need to be exposed in the GUI or enabled by default. It simply needs to exist for those of us who need it and fully understand the risks.

Right now, Windows 11 24H2 breaks all file sharing support for MS-DOS and other legacy clients. If this change remains permanent, retro computing users will be forced to remain on Windows 10 indefinitely or move to non-Microsoft solutions to retain functionality that has existed for decades.

Please do not abandon retro users who rely on this. Provide a way to restore NTLMv1 in controlled environments. Removing it entirely without a fallback path is unacceptable to a large and passionate part of your community.