Hello,
Follow the Below steps,
- Go to the Internet Information services (IIS) manager.
- Select your Application Pool which you have given in Business portal site.
- Right click on Application pool and go to Advanced settings.
- In Advanced Settings, select the Identity under Process Model.
- Opens up the Application Pool identity pop up window.
- Select the custom account option and click the set button
- Opens up the set credentials pop up window and you have to provide the Username, Password & Confirm Password.
- Click ok.
- Go to Run (Windows + R) and type IISReset to restart the IIS manager.
- Take the backup of Business portal databases.
- Re run the Share point central administrator wizard to re configure the User Account.
Hope this will help
Thanks,
Perumalsamy R