Failed to login to destination "Azure (UK South)" with credentials provided, Reason = "[B] [CloudException.LoginFailedExpt]

Error

com.ahsay.afc.cloud.f: Failed to log in to destination "Azure (UK South)" with the credentials provided, Reason = "[B] [CloudException.LoginFailedExpt] Failed to log in 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

The system clock on the device is wrong.

When backing up to Azure Blob Storage, every request includes the time it was sent. Azure checks that time against its own clock, and rejects the request if the device’s clock is too far ahead or behind (Azure allows about 15 minutes’ difference). This protects against old requests being captured and replayed. Azure then returns the authentication error above, even though the storage account details are correct.

In Azure’s own logs, this usually shows as an HTTP 403 error, such as AuthenticationFailed or Signature not valid in the specified time frame.

Fix

Check the date, time and time zone on the device.
Sync the clock. On Windows, open Settings → Time & language → Date & time and click Sync now. Or open Command Prompt as administrator and run:
```
w32tm /resync
```
On a domain-joined device, the clock syncs with the domain controller, so check the domain controller’s time too.
Run the backup again.

See also Microsoft’s guide to troubleshooting Azure Storage 403 errors.