Abstract—Writing correct multithreaded programs is difﬁcult.
Existing tools for ﬁnding bugs in multithreaded programs pri-
marily focus on ﬁnding generic concurrency problems such as
data races, atomicity violations, and deadlocks. However, these
generic bugs may sometimes be benign and may not help to catch
other functional errors in multithreaded programs. In this paper,
we focus on a high-level programming error, called typestate
error, which happens when a program does not follow the correct
usage protocol of an object. We present a novel technique that
ﬁnds typestate errors in multithreaded programs by looking at a
successful execution. An appealing aspect of our technique is that
it not only ﬁnds typestate errors that occur during a program
execution, but also many other typestate errors that could have
occurred in a different execution. We have implemented this
technique in a prototype tool for Java and have experimented it
with a number of real-world Java programs.