Data refresh failed. Please try again later or contact your administrator.

We have built a new Power BI Report Server.
The Power Bi Report Server is installed in the database and the server specifications are as follows.

[Previous System]
- Operating system: Window Server 2016 (on-premise)
- DataBase : MSSQL2016
- Power BI Report Server Version : 15.0.1106.169 (2019, Jan)
[New System]
- Operating system: Window Server 2019 (cloud)
- DataBase : MSSQL2016
- Power BI Report Server Version : 15.0.1112.79 (2023, May)

The following is the order of the work done.
1. Back up the Report Server DataBase of the previous system to the .bak file and back up the Key of the Report Server
2. After installing Window Server 2019 on the new system, install MSSQL2016 and restore Report Server DataBase from .bak file
3. Install the Power BI Report Server (15.0.1112.79 (2023, May) on the new system and restore the key
4. Add MASTER, MSDB role, and permissions to the new system (RSExecRole)
5. Check the normal operation of all functions in the PowerBI Web Portal Page.
6. Check the normal operation of adding/deleting folders, permissions, adding/deleting users among PowerBI APIs
7. Check file upload operation failure during PowerBI API
8. PowerBI Desktop editing failure check

The following are some of the relevant error messages.
1. [SubscriptionHistory] Log
- Message : Data refresh failed. Please try again later or contact your administrator.
- Details : {"SessionID":"xxx","Errors":[{"ErrorCode":0,"Message":"Model can not be refreshed with no connection string",~~"}]}

2. PowerBi Error Log
- |WARN|12|Received a request with an unmatched or no authentication scheme. 401
- |ERROR|35|Error Processing Data Model Refresh: SessionId: xxx, Status: Error Model can not be refreshed because not all connection string is valid ~~

Comparing all the config files of the old and new systems (\PBIRS\ASEEngine, \PBIRS\Office, \PBIRS\Portal, \PBIRS\PowerBI, \PBIRS\ReportServer) did not find any differences other than the version, and the service execution accounts are all the same.
What did we miss?
We desperately need the help of our masters! T_T