Hello Sree,
Error log is pointing to LastChangedTime property getting filled with invalid format.
Debugging would help to find the exact issue here.
Have you set LastChangedTime property to nullable ?
If not please do this also in model and re-generate objects and clear the cache and check again.
/IWFND/CACHE_CLEANUP
/IWBEP/CACHE_CLEANUP
Regards,
Ashwin