Unauthenticated, guest access, security policies - the message is three technical phrases stacked together. Decoded into plain words, it points at one exact cause and one exact fix.
Most Windows errors are useless riddles. This one is the opposite - it is a precise sentence wearing formal clothes. You can't access this shared folder because your organization's security policies block unauthenticated guest access contains the cause, the culprit and the cure, if you read it word by word. This page does exactly that, including the part of the dialog most people ignore: the error code underneath, which quietly confirms which problem you have - and rules out the lookalike errors that need completely different fixes.
An example share address. Four lines, and only the second one matters - the rest is the standard frame Windows puts around every sharing refusal.
Unauthenticated simply means: no identity was proven. When you open a share, Windows and the other device are supposed to exchange proof - a username and password. In the guest case, that exchange never happens. Your PC knocks, the share says come in, nobody shows any ID. Windows is not complaining that your password is wrong; it is complaining that no password was involved at all. That distinction matters, because retyping passwords into the prompt will never fix a problem whose entire point is that there is no password.
A guest is a share's open-door mode. NAS boxes, routers with USB drives and many Linux file servers offer it so any device on the network can walk in - convenient on day one, dangerous forever after, because the door cannot tell your laptop from a stranger's. The guest in this error lives on the server side: it is the share that offers entry without a login. Your PC is the bouncer refusing to use that door. People often hunt for a guest setting on their own PC to switch off; the setting that matters is on the device holding the files, and the real fix is to give that device a proper user account.
The most confusing phrase for home users. There is no organization. Microsoft writes these messages once, for offices and homes alike, and the policy it refers to is a built-in Windows default - a rule the operating system carries itself. Depending on your edition, that rule has been there for years: guest fallback was switched off in Windows 10 Enterprise, Education and Pro for Workstations editions from version 1709, and Windows 11 Pro switched it off by default as well. Windows 11 version 24H2 then added required SMB signing on top. Nothing was installed on your PC by an employer; the operating system simply grew stricter, on purpose.
This refusal often travels with error code 0x80004005, which literally means unspecified error - Windows knows it refused, and did not bother to give the refusal its own number. Do not let that send you down generic 0x80004005 guides. Read the sentence, not the code. And separate this error from its two lookalikes:
0x80070035 - the network path was not found. The PC never reached the share: wrong address, device off or asleep, or sharing not running. A reachability problem, fixed by checking the device and the address - not by any guest settingIt is refusing to start a session with zero proof on either side. A guest session cannot be signed - there is no credential to sign it with - so on current Windows the traffic also cannot be protected against tampering or relaying. Microsoft's own summary: a PC that accepts guest logons can be tricked into connecting to a malicious server without ever being asked for credentials. The error is that protection firing correctly. Treat it as a diagnosis, not a malfunction: your share is set up in a way Windows retired, and the two honest exits are give the share a login, or knowingly switch the protection off for one trusted home device.
Watch the error appear in the video and the same setting this guide decodes being switched, so you can match message to fix.
▶️ Watch Full VideoNew PCs ship with current Windows, where the guest block and, in 24H2, required SMB signing are on by default. An older PC may run an edition or version where guest fallback was still allowed. Same share, stricter bouncer.
If the dialog carries the guest access sentence, yes - 0x80004005 is the generic code Windows attaches when it has no specific number for the refusal. The sentence is the diagnosis. If your 0x80004005 comes without that sentence, it is a different problem and this guide does not apply.
Only by switching off the protection on your PC - the AllowInsecureGuestAuth setting. That makes the message disappear by removing the guard, not by fixing the cause. It is documented and sometimes necessary for an old home NAS, but it is a deliberate downgrade and should be the last resort, at home, on a network you trust.