Found on StackOverflow
int result = Translator.start(mContext, new Translator.ServiceListener() {
.....
}
it return ERROR_APP_MISSING_SIGNATURE = 51; in kitkat, but its work fine in marshmallow and later android api versions
Workaround for now:
change the check in checkAppSignature() method of TranslatorImpl.java to:
if (packageInfo == null || packageInfo.signatures == null || packageInfo.signatures.length == 0) {