Hi Anushree,
Now I realized the issue. I was accessing my MII server through Remote Desktop Connection and my jar files were stored on local machine. I used to upload the custom action jar files from my local machine. I think while browsing jar files from local machine created the issue (jar files might have corrupted). Now I copied the jar files to the MII server and browsed from there which worked.
Sorry for wasting your time.
I appreciate your continuous support again
Thanks
Shaji