@SMANUEL ,

As per the details seems this issue could be due to permission issues with the outlook. Simply you can try out running the outlook client as the Administrator and check whether the issues still exist.

Below is a fix gave to the same sort of issue.

https://www.kunal-chowdhury.com/2018/01/outlook-addin-disable-admin-error.html?ts=1616602823329&utm_source=Bing&utm_medium=organic

Hi @SMANUEL 

Can I know which installation method you used to install the BR client and whether you use your local machine to install BR? 

Further please go through the below steps again when installing

1. Uninstall the current version of BR 
2. Install BR client using MSI if you have the admin privileges to install BR client. When you are trying to install the BR client, could you please use the “Just Me” option in the wizard instead of “Everyone”?
3. If you are using ClickOnce to install, please check if the addon is still there in COM addins. If so remove it and reinstall. 

Regards,
Dilmi. 

@Dilmi Gunasiri  @Charith Epasinghe  Thank you for your reply..

ClickOnce ..We recently upgraded to version : 5.0.19.0..

We will try what Charith suggested as this looks like the issue with one particular user..

For others, we are yet to install the new version..We will surely follow what Dilmi suggested and keep you posted..

Thanks Much guys 

Hi @SMANUEL ,

May be this error is raised when BR client installation/uninstallation is not happened properly. In such a scenario you can remove it from Excel with following steps.

Open Excel as an Administrator.

Go to File-> Options -> Add-ins

Select Com-Add ins from Manage Drop down -> click Go

It will open the below dialog
You can either remove the Add-in or select the add-in to make it available. 
 

Best Regards,

Nisansala