Generate Signed APK using Android Studio 3.1.3 - android-studio

Question

I am pretty sure that I have checked all the possible duplicate questions and none solve my problem. I have instant run turned off, I have minfy and shrink set to false. I have cleaned. The keyfile exists and worked perfectly on a previous release of this app. I have tried running the compile with --info but it does not give me any hints as the the problem. The error is:
Execution failed for task ':app:packageRelease'.
Failed to read key myreleasekey from store "C:\Users\Mel\AndroidStudioProjects\tourbuilderkeystore.jks": Cannot recover key
My build gradle is:
apply plugin: 'com.android.application'
android {
compileSdkVersion 27
buildToolsVersion '27.0.3'
defaultConfig {
applicationId "com.myguidedtours.www.tourguide"
minSdkVersion 16
targetSdkVersion 27
versionCode 10
versionName '1.10'
}
buildTypes {
release {
minifyEnabled false
shrinkResources false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
productFlavors {
}
}
dependencies {
// implementation fileTree(include: ['*.jar'], dir: 'libs')
implementation 'com.android.support:appcompat-v7:27.1.1'
implementation 'com.android.support:support-fragment:27.1.1'
implementation 'com.android.support:support-compat:27.1.1'
implementation 'com.google.android.gms:play-services-maps:15.0.1'
implementation 'com.google.android.gms:play-services-base:15.0.1'
implementation 'com.google.android.gms:play-services-tasks:15.0.1'
implementation 'com.google.android.gms:play-services-basement:15.0.1'
implementation 'com.android.support:mediarouter-v7:27.1.1'
implementation 'com.android.support:support-v4:27.1.1'
implementation "com.android.support:exifinterface:27.1.1"
implementation files('libs/PdfViewer.jar')
}
I have been sweating over this for two days - I hope you can help.

Answer 1

Just in case there's someone out there as stupid as me. The prompt for Generate a Signed APK in Android Studio, does not tell you if the passwords you supply are good or bad. I must have miss-keyed one of them, then, because I ticked the remember passwords option, it failed every time I tried to run it. There is no hint that the password may be wrong - usually when you enter a bad password you get immediate feedback.