Hi,
This forum is for technical support on Blizzard’s Classic (ie, legacy) Games such as Diablo II (2000).
For your issue, you will need to contact Activision Support for help; see the following for details:
Finally, Activision’s Known Issues in Call of Duty: Warzone Caldera page states that “An issue leading to Dev Error 5476 is under investigation.”.
Good luck with this.