java.lang.VerifyError: Verifier rejected class on Lollipop when using release APK

Cleaning out the build folder resolved the problem. Not sure why ART had an issue but Dalvik did not.

Running a gradle clean task was not clearing out my build folder all the way. I had to do it manually, but clean may work for some people.

In my case, the cause was slightly different.

Apparently, putting a synchronized statement inside a try/catch block causes the VerifyError, as reported here on SO and on the official bug tracker.

In my case the method that the error message said was 'bad', had some unknown faults. Changing from a Kotlin lambda to a regular loop solved my issue.

Before (With Error):

fun validZipCode(zipcode: String): Boolean {
    val validRegexes = arrayOf(
            "0[0-9]{1}[0-9]{2}", 
            "1[0-2]{1}[0-9]{2}", 
            "1[3-4]{1}[0-9]{2}", 
            "19[0-9]{2}", 
            "2[0-1]{1}[0-9]{2}" 
    )
return validRegexes.any { zipcode.matches(it.toRegex()) }

After:

fun validZipCode(zipcode: String): Boolean {

    val validRegexes = arrayOf(
            "0[0-9]{1}[0-9]{2}", 
            "1[0-2]{1}[0-9]{2}", 
            "1[3-4]{1}[0-9]{2}",
            "19[0-9]{2}", 
            "2[0-1]{1}[0-9]{2}"
    )

    for (regex in validRegexes) {
        if (zipcode.matches(regex.toRegex())) {
            return true
        }
    }

    return false
}