# \[SOLVED\]runPrepUpdate is failing to return a value

**URL:** <https://forum.inductiveautomation.com/t/solved-runprepupdate-is-failing-to-return-a-value/33173>\
**Category:** Ignition\
**Created:** [March 17, 2020, 5:12pm UTC](https://forum.inductiveautomation.com/t/solved-runprepupdate-is-failing-to-return-a-value/33173 "2020-03-17T17:12:18Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [March 17, 2020, 7:39pm UTC](https://forum.inductiveautomation.com/t/solved-runprepupdate-is-failing-to-return-a-value/33173/5 "2020-03-17T19:39:43Z")

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Python's Exception classes inherit from PyObject, while java exceptions inherit from java.lang.Throwable. They simply don't have a common parent class, so can only be caught in the same except clause when you specify no exception class at all. If you need to catch them both with the explicit syntax, use two except clauses.

See also:

> [@Catch IOException?](http://forum.inductiveautomation.com/t/catch-ioexception/18612/3):
>
> Consider using two except blocks, as jython’s standard Exception won’t catch pure java exceptions. Like so: import java.lang.Exception try: # something something something except Exception, e: # jython exception except java.lang.Exception, e: # java exception

Also note that java exceptions can have a chain of "causes" you can follow for more detail. Though some of that detail is lost in serialization when exceptions are reported from gateway to client.

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