I am posting this to simply identify the bug and how to solve it.
I) We are facing the following problem while changing the server IP address or name.
The following area we need to check whether the server name/IP address correct or not.
\Program Files\SAP\SAP Business One\Conf
\Program Files\SAP\SAP Business One DI API\Conf
If it is wrong, we have to change correct one.
Finally restart service manager. It will work.
II) Add-On installation problem
If the add-on already connected with the company in the same name, we have to stop it.
Check the task manager if the same add-on is running, we have to stop it.
Also clear %temp% file.
Confirm it you have authorization for installation.
Then try it…