Error Fixes5 min read·Apr 11, 2026

Windows Cannot Access \\PCNAME — Error Code 0x80070043 (Fix)

Error 0x80070043 means Windows found the machine but cannot reach the share. Here is exactly why it happens and the step-by-step fix.

What This Error Means

Windows cannot access \PCNAME\ShareName Error code: 0x80070043 The network name cannot be found.

This error is distinct from 0x80070035. The key difference:

  • 0x80070035 — Windows cannot find the machine at all (path resolution failed)
  • 0x80070043 — Windows found the machine but cannot reach the specific share name

The host machine is on the network. The path to it resolves. But when Windows attempts to connect to the named share on that machine, the share either does not exist, is not responding, or is being blocked.

Root Cause 1 — The Share Name Does Not Exist

The most straightforward cause: the share name in your path does not match any share on the host machine. This happens when:

  • The folder was renamed or the share was deleted
  • The path has a typo (\\HOSTNAME\Project when the share is named Projects)
  • The share was on a different machine

Fix — Verify the exact share names on the host: On the host machine, open PowerShell and run:

Get-SmbShare | Select-Object Name, Path

This lists every share and its exact name. Match it against what you are typing.

Or browse directly: On the connecting machine, type just \\HOSTNAME (without a share name) in the File Explorer address bar. If any shares exist and are accessible, Windows shows them as a folder list.

Root Cause 2 — SMB Service Is Not Running on the Host

The SMB Server service (LanmanServer) must be running for any shares to be accessible.

Fix: On the host machine, open PowerShell as Administrator:

Get-Service LanmanServer

If it shows Stopped:

Set-Service LanmanServer -StartupType Automatic
Start-Service LanmanServer

Root Cause 3 — Windows Firewall Blocking Port 445

SMB uses TCP port 445. If the host machine's firewall blocks incoming connections on port 445, shares are unreachable even though the machine itself is visible on the network.

Fix: On the host machine:

  1. Control Panel → Windows Defender Firewall → Advanced Settings
  2. Inbound Rules → look for "File and Printer Sharing (SMB-In)"
  3. If it shows a red circle (disabled): right-click → Enable Rule
  4. Confirm the rule applies to the Private profile

Test the port from the connecting machine (PowerShell):

Test-NetConnection -ComputerName HOSTNAME -Port 445

If TcpTestSucceeded shows False, port 445 is blocked.

Root Cause 4 — Host Machine Network Profile Is Public

Fix: Settings → Network and Internet → your active connection → Network Profile Type → Private network

With Public profile, the host machine does not accept incoming SMB connections regardless of firewall rules or share configuration.

Root Cause 5 — SMB2 or SMB3 Not Negotiating Correctly

In some configurations, the SMB version negotiation fails silently, causing 0x80070043.

Check SMB server configuration on the host:

Get-SmbServerConfiguration | Select-Object EnableSMB2Protocol

If EnableSMB2Protocol shows False:

Set-SmbServerConfiguration -EnableSMB2Protocol $true -Force

Root Cause 6 — Third-Party Security Software

Security suites with "network protection" features (Kaspersky Internet Security, Norton 360, ESET Smart Security) sometimes block incoming SMB even when Windows Firewall is correctly configured.

Test: Temporarily disable the third-party security suite on the host machine and retry. If connection succeeds, add a rule in the security suite to allow SMB traffic from the private network subnet.

Step-by-Step Diagnostic

  1. Type \\HOSTNAME only (no share name) — if you see a list of shares, the host is accessible and the share name is the problem
  2. Run Get-SmbShare on the host to confirm the share exists
  3. Run Test-NetConnection HOSTNAME -Port 445 from the client — if TcpTestSucceeded is False, port 445 is blocked
  4. Check network profile on the host — must be Private
  5. Check LanmanServer service — must be Running

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Frequently Asked Questions

The share is visible when I type \\HOSTNAME but clicking it gives 0x80070043. Why? You can see the share exists (the discovery works) but connecting to it fails. This is usually a firewall rule that allows the SSDP/WS-Discovery announcements but blocks the actual SMB data connection on port 445. Check the firewall rules for "File and Printer Sharing (SMB-In)."

Error only appears after the host machine restarts. Why? The LanmanServer service may not be starting automatically. Check its startup type is Automatic (Set-Service LanmanServer -StartupType Automatic).

We see this error on some machines but not others connecting to the same share. Why? The issue is client-side on the affected machines. Most common cause: a conflicting or stale entry in Windows Credential Manager for the host. Control Panel → Credential Manager → Windows Credentials → remove entries for the host machine, retry.

Does this error appear on Mac or Linux? The error code is Windows-specific, but Mac users see "Connection Failed" when the same underlying conditions apply (SMB service down, share does not exist, port 445 blocked). The same diagnostic steps apply — verify the share exists and port 445 is open.

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