<p>When I get a java.io.InvalidClassException, it gives me the serialVersionUID that it wants, and the serialVersionUID that it got.  Is there an easy way to tell which of my dozens of jars using the wrong serialVersionUID?</p>

<p><strong>Update</strong>: I should mention that our intention is to update everything at the same time, but I'm trying to debug a problem in our build and deploy process.</p>

The best way to deal with this kind of trouble is to update jars on the server and client side at the same time. This will guarantee the same version of your classes on both sides and you'll not have trouble when serializing / deserializing. Tracking serial UIDs each time you have this problem is not going to solve anything, you're only going to waste considerable time and resources. Its much better to spend some time and implement a proper deployment / packaging strategy.
If you really don't have any other choice, you can write a tool that loads a class from each jar (using a URLClassLoader) and then use
```
java.io.ObjectStreamClass.getSerialVersionUID()
```
to obtain the information you need.