Thanks for trying to help.
I just downloaded drools-5.1.0.SNAPSHOT-bin from  - which I found in a thread from this mailing list - and changed my drools runtime in Eclipse. Since then, it seems that all my problems are solved! There are no weird errors anymore ;)
In any case, I'm using Drools 5, and yes, I'm compiling and executing with the same version.

Thanks anyway!

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From: Kris Verlaenen <>
To: Rules Users List <>
Date: 14/09/2009 10:59
Subject: Re: [rules-users] java.lang.NoSuchMethodError on every Action node
Sent by:

Whenever you add a Java action in your process, the compiler will
generate a Java class in the background that will be used for executing
this action.  The error seems to indicate that the class generated by
the compiler is not what the runtime is expecting.  Which version of
Drools are you using?  And are you compiling and executing with the same
version (or are you for example first building your knowledge base and
then serializing your package or getting it from guvnor)?

If possible, could you include a sample project that shows the issue, so
I could take a look what's going on at runtime?


> This time, every action I try to insert in a ruleflow, I receive a
> java.lang.NoSuchMethodError. I'm even trying a really simple ruleflow
> with
> just one simple action - like System.out.println("Test"); - and all I
> get
> is a java.lang.NoSuchMethodError.

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