Hello @shankar.arekonda.external ,
It looks like the Selector indicated by you in attach browser is not valid.
If you already have a Login sequence and used Open Browser activity then use a Browservariable in the Output Property of Open Browser activity and pass the same Browservariable in Input - > Browser Property of Attach Browser Activity.
Please refer to the academy courses for more details on the selector and Ui Automation.
It is just a selector error, just dont give tags which have dynamic values and try to reduce the no of tags used just give app=chrome and title=“SAP Concur Home” and remove other tags
You can try with Asterisk for more dynamic
<wnd app='chrome.exe' cls='Chrome_*' title='SAP*'>