Flow designer not allow to save and thrown out error

[sukran]

While saving the flow its thrown an error saying 

"Unknown error occurred while processing request , check logs to get more information"

[Sainath N]

@sukran : please check if the below HI article helps.

https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB1219673

Please mark this as correct answer and helpful if it resolved, or mark this helpful if this help you to reach towards solution.

[Dr Atul G- LNG]

Hi @sukran 

Check here

https://www.servicenow.com/community/developer-forum/flow-designer-where-can-i-access-the-log/m-p/17...

[Dr Atul G- LNG]

[sukran · Accepted solution]

Found the solution 

Issue causing after upgrade to vancouver .. The flow trigger condition previous versions UI , can able to select directly as Service Catalog :

But In Vancouver we have to choose Trigger condition as Application -> ServiceCatalog " 

The UI selection is different in vancouver which causing existing flow for save