I would suspect either they were not properly installed on the target server and might have got corrupted or the java services might be making calls to IS internal(private) methods which are no longer available(deprecated).
If you have this package properly installed on a different server then try to do an export of the package or use Deployer to install it to the server where this issue exists and see if that fixes it.
Thanks for the pointers but that doesnt seem to be the case for us. The package was disabled as in certain servers as it was not required there, along with few other packages.
The same package is active and working as expected.
Yes, I had installed the package from other servers in which it was active.
Wanted to know if anyone else has faced this issue and if they were able to figure out why it has happened.
I did face this issue when i did a physical copy of the package directory from one server to another server not long ago and restarted the IS. I could not activate the package after that copy and restart. I had to do a hard delete of the copied package and the install it again by getting an export and placing it in inbound directory.
Another thing you could do is to do a file level comparison from the package that is non-active on a server with the package that is active. May be that might give you some direction.