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ERROR_SMB1_NOT_AVAILABLE
The file share depends on the disabled SMB1 protocol
ERROR_SMB1_NOT_AVAILABLE is a Win32 system result. Modern Windows disables or removes SMB1 because the protocol lacks current security protections. The error usually points to an old NAS device, appliance, embedded system, or server configuration rather than to bad credentials.
What the result means
The remote share requires obsolete SMB1, but the client permits only SMB2 or newer. For ERROR_SMB1_NOT_AVAILABLE, keep the symbolic name, numeric value, and failing operation together in diagnostics; that combination distinguishes the exact failure path from nearby system results.
What to check
- Identify the exact server or device and verify which SMB dialects it supports.
- Update firmware or server configuration to enable SMB2 or SMB3.
- Confirm that DNS or an alias is not directing the client to an older endpoint.
- Do not enable SMB1 broadly as a first-line workaround.
Recommended handling
Upgrade or replace the server-side component, or isolate and migrate the data through a controlled compatibility environment. Enabling SMB1 increases attack exposure and should only be considered under explicit risk management.
Developer notes
Report the protocol mismatch clearly instead of prompting repeatedly for credentials. Inventory legacy dependencies and test dialect negotiation during deployment. When a Win32 API reports ERROR_SMB1_NOT_AVAILABLE, capture GetLastError() immediately; subsequent cleanup, formatting, or logging calls can replace the thread-local value.
References
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