Sage 300 was working fine and the next day the user was getting the error "Could not open the UI. the system may be busy because another application (such data conversation application) has locked the company's database. Other wise the UI was not opened because unexpected error has occurred" when trying to open any icon on Sage.

After checking the recent updates and searching for any change in the environment we noticed that MalwareBytes was running in the background. We checked this program and noticed that some Sage dll files were in quarantine.

We whitelisted the Sage runtime folder in Malwarebytes and resolved the issue.