We were facing same issue on 8.1 SP2.
After replacing jar file it got fixed.
The same jar file works for 8.1 SP3 as well and it is needed to fix the Shavlik issue. Don't know why it says that SP3 had the fix
SP3 did have the fix.
Did you leave the old jar w/ a .jar extension in the stdlib dir ?
Yes, this was the problem. I'm not sure why it worked prior to upgrading with the (renamed) .jar file in the same directory, but removing it from the directory and restarting the application server worked.
The fix is included in sp3.