"Unfortunately Has Stopped" Only in Release Version

I am getting an "Unfortunately Has Stopped" message in my release version that does not occur in the debug version. This happens both on my S4 mini and on the Samsung RTL devices. The debug version works on all of these devices plus on the Genymotion emulators. The error occurs using Jsoup when i tap my menu choice which activates Jsoup.connect.

I determined that the problem is caused by ProGuard, by following a suggestion to disable ProGuard. The program runs if i change minifyEnabled to false or if i simply delete the two lines ...
buildTypes {
release {
minifyEnabled true
proguardFiles getDefaultProguardFile('proguard-android.txt'),'proguard-rules.pro'
}
Now i do not know what to do next. I do not want to post a bunch of code etc since i do not know what is needed. Also i do not know how to run the release APK with debugging or how to get a stack trace or other debugging information from a release build.

BTW, every line of my build.gradle file is haunted by the "cannot be applied to '(groovy.lang.Closure)'" warnings, but my research tells me that this a harmless Android Studio bug with no reliable workaround and would be unrelated.

I have a feeling that this is a common problem with a well known solution but i have not been able to find much discussion on various forums. Any guidance much appreciated,
Mick