It happens when you first launch Notes client

Notes/Domino 8 Forum

Subject:

Try this solution:
1. Close Notes client and Notes designer;
2. Launch only notes designer;
3. Open lib causing error that uses *javacon
4. Add whatever to the code (i.e. space) and delete it and then save lib to force it recompile.
5. Open other libs causing errors, that use lib mentioned in step 3. and repeat step 4.

I read somewhere here, that the error raises when java console from Notes Client interferes with Notes Designer. When you remember to launch designer first, you shouldn't have such problems.

Feedback response number WEBB992CKK created by ~Xagra Zekalitynds on 06/26/2013