"Error while executing background thread HTTP Refresh Service" after upgrade to 2.5.6-1


after upgrading to 2.5.6-1, I constantly get the following log messages thrown in a high frequence (like once a second).

2020-06-22 14:25:14.418 [ERROR] [b.core.service.AbstractActiveService] - Error while executing background thread HTTP Refresh Service
java.lang.NullPointerException: null
	at org.openhab.transform.javascript.internal.JavaScriptEngineManager.getScript(JavaScriptEngineManager.java:68) ~[?:?]
	at org.openhab.transform.javascript.internal.JavaScriptTransformationService.transform(JavaScriptTransformationService.java:74) ~[?:?]
	at org.openhab.core.transform.TransformationHelper$TransformationServiceDelegate.transform(TransformationHelper.java:69) ~[bundleFile:?]
	at org.openhab.binding.http.internal.HttpBinding.execute(HttpBinding.java:218) ~[?:?]
	at org.openhab.core.binding.AbstractActiveBinding$BindingActiveService.execute(AbstractActiveBinding.java:146) ~[bundleFile:?]
	at org.openhab.core.service.AbstractActiveService$RefreshThread.run(AbstractActiveService.java:169) [bundleFile:?]

I tried to turn off the logging with log:set OFF <ID> for the HTTP-Binding, the Transformation Core and the JavaScript-Transformation-Service, but the logs keep popping up.

Does anyone know why this error is caused and - as a side question - why I cannot turn off the logs?

To avoid damage to my SD card caused by high I/O I temporarily made a link to /dev/null as /var/log/openhab2/openhab.log - and of course I’d like to get rid of that asap.

There is a bug introduced in 2.5.6-1 that was quickly fixed and a new release made (2.5.6-2). A search of the forum would reveal many postings in this problem. An upgrade to the new -2 release should fix the problem.

The location of the bug

Thank you for your response and the hint with the new version. I am using openHABian, but updating the system using openhabian-config does not install 2.5.6-2. Am I missing something?

Using the search for " “Error while executing background thread HTTP Refresh Service” does in fact only displays one post from before 10 days, this post and older posts from 2018. I am sorry I have missed the other posts, but I seem to be using the search incorrectly somehow?

The bug is about javascript transformation, which gets used in a great many different parts of openHAB. It’s not specific to HTTP, and could show up in the context of rules or other bindings or profiles or labels. It is difficult to know which part of the error logged is the significant part.