Start by showing us the log before the failure so we can see the versions of everthing. Also what hardware and operating system are you running on?
am using windows10. where can i find the log file ?
You've shown us a screenshot of the log in your first post. We'd like to see the first few lines of the output that tells us what versions of everything you're using.
As you are Node-RED v0.20.x you can start with the
--safe flag ( which is why it's useful to see the version numbers) https://nodered.org/blog/2019/03/12/version-0-20-released#runtime
You can then edit your ui-template and deploy and restart Node-RED.
You also aren't using the latest version of the dashboard, perhaps its a good time to update?