Error
com.ahsay.afc.cloud.f: Failed to login to destination “Azure (UK South)” with the credentials provided, Reason = "[B] [CloudException.LoginFailedExpt] Failed to login to cloud service with the credentials provided.
Error=‘Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.’, caused by [StorageException] Server failed to authenticate the request.
Cause
This error occurs when backing up to Microsoft Azure Blob Storage, and the system clock on your device is incorrect.
Microsoft’s cloud is parsing the error to our service to prevent any risk of data corruption that can occur when system clocks are out of sync.
When the system clock on a client or server is wrong, authentication to Azure Blob Storage commonly fails. This is expected behaviour and is caused by time-based validation built into Azure’s security model.
Why Azure Blob login fails if the system clock is wrong
Azure Blob Storage validates timestamps during authentication. If the local machine’s clock is too far ahead or behind Azure’s servers, requests are rejected.
This affects all common authentication methods:
- Shared Access Signatures (SAS)
- OAuth / Entra ID (Azure AD) tokens
- Account key–based authentication
Azure enforces this to prevent replay attacks and expired-token misuse. If the request’s timestamp is outside the valid window, authentication fails immediately. [learn.microsoft.com]
Typical errors you will see
When clock skew is the root cause, Azure usually returns HTTP 403 errors with messages such as:
AuthenticationFailedSignature not valid in the specified time frameSigned expiry time must be after signed start timeSAS token has expiredToken not yet valid
Microsoft explicitly documents clock skew as a common cause of these errors. [learn.microsoft.com]
Fix
Check that the system clock on your device is correct.
