Github user Mingun commented on the issue: https://github.com/apache/jmeter/pull/394 Thanks! I was tested with 2c82bf31db1110919e9ab84b13ab6c4f15d92ac5 (trunk branch). The exception does not arise any more though to set *Undefined* value for File property is impossible now, even though the flag {{NOT_UNDEFINED}} is not set for property. I attach 2 screenshots showing behavior of the same plugin file in versions 3.1 and 5.1: ![jmeter 3 x](https://user-images.githubusercontent.com/450131/46124740-415ad480-c23f-11e8-89bd-58d0f2ac73b3.png) ![jmeter 5 x](https://user-images.githubusercontent.com/450131/46124742-415ad480-c23f-11e8-9435-d56dc8dabab0.png) Therefore this fix so far not really helps me
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