A Microsoft file hosting and synchronization service.
Hi Andy,
Regarding the error code, it's like an Internet connection issue. Here are some references:
Thread - Error Code 0x8004de40
Thread - OneDrive not signing in
Video - Fix error code 0x8004de40 while connecting to OneDrive for Windows
If the issue remains, please share your OneDrive for Business sync client version number with us. Right click the icon > settings > About > version.
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Thanks,
Jim