In the previous Go 4 app version, I only needed to pair/ID the Go 4 app  with my Spark Controller once but with the upgrade (v4.2.4) I have to re scan the  QR code every time I wish to use my Spark. Is this a feature or am I doing something wrong?

I would suggest not using the QR code at all.  Just go into your phone's wifi settings, select the SPARK-RC SSID and supply the password.  Once you do it this way, it will be saved and any time you aren't already connected to a WiFi connection, it will automatically connect to it.  However, if you are at home and are already connected to your home's wifi, you may have to go to your WiFi settings and choose the SPARK-RC.

Try upgrading again to 4.2.5 - some bug fixes are in that

start spark  
start the rc .  
let sit be patient
Spark flashes continuously yellow rear 2 (looking to hook up w/ something within .6 meters 20 inches or so if not hold power button on spark till you here 1 beep... should now be blinking rear 2 yellow.
The blinking Rc green light will go solid green as the Rc connects to spark),
start mobile device go4 app. patience again here once started select spark.
go to mobile device settings.
Turn Wifi on/ No OTG cable (for android users ) or
for IOS users turn wifi off.(otg cable connection is working) .
connect mobile device to Rc controller via otg cable.
android version otg cable direct will not work...
DJI I'm certain is working on next update

Hi, there. I would recommend users use 4.2.5 version of app and see if the problem remains. Please keep us updated, thanks for your support.

DJI Elektra Posted at 2018-2-7 20:21
Hi, there. I would recommend users use 4.2.5 version of app and see if the problem remains. Please keep us updated, thanks for your support.

Just tried Google Play Store and latest version was v4.2.4 , so I am not sure if v4.2.5 is the latest version for iPhone. Can't  download the APP from the DJI download page so Play Store is the only choice.
The latest improvements to the App and the firmware are really good but this would appear to be a bug. My phone is an S8 plus and manages most apps well, so I think this is a coding issue. The old app I was using didn't have the problem but the QR code method was a great idea. I would prefer only to do it once and not when I'm photographing.
Cheers.

Try with Spark already connected to the RC when you start the GO4.

Kloo Gee Posted at 2018-2-7 08:20
I would suggest not using the QR code at all.  Just go into your phone's wifi settings, select the SPARK-RC SSID and supply the password.  Once you do it this way, it will be saved and any time you aren't already connected to a WiFi connection, it will automatically connect to it.  However, if you are at home and are already connected to your home's wifi, you may have to go to your WiFi settings and choose the SPARK-RC.

Thanks Kloo Gee you appear to have this correct. The QR code system isn't as good as setting the WiFi manually but the odd thing is , I already had the WiFi setup for my controller. The WiFi doesn't always connect to the controller when it sees it.
I will repeat the exercise tomorrow and see what happens.

Cheers and thanks.

S-e-ven Posted at 2018-2-7 22:11
Try with Spark already connected to the RC when you start the GO4.

I did try that and it didn't seem to be the problem however it could be part of the issue. I had trouble with this on the old app and an older phone. Android OS turned out to be culprit.

Cheers

Hotwire Posted at 2018-2-7 22:16
Thanks Kloo Gee you appear to have this correct. The QR code system isn't as good as setting the WiFi manually but the odd thing is , I already had the WiFi setup for my controller. The WiFi doesn't always connect to the controller when it sees it.
I will repeat the exercise tomorrow and see what happens.

Is your phone's WiFi already connected to another hotspot when it doesn't directly connect to the Spark's?  That is how mine works.  If I'm already connected to a WiFi connection (such as my home Wifi), then it will stay connected to it.  However, if I'm out and about and not already connected, then it will automatically connect to the Spark's.  

I don't know about Android, but on iOS, in the WiFi settings, you can configure a connection to auto-join to it or not.  Might be worth it to check the options of that connection and see if the Spark's connection is set to auto-join on your phone.

Kloo Gee Posted at 2018-2-8 12:48
Is your phone's WiFi already connected to another hotspot when it doesn't directly connect to the Spark's?  That is how mine works.  If I'm already connected to a WiFi connection (such as my home Wifi), then it will stay connected to it.  However, if I'm out and about and not already connected, then it will automatically connect to the Spark's.  

I don't know about Android, but on iOS, in the WiFi settings, you can configure a connection to auto-join to it or not.  Might be worth it to check the options of that connection and see if the Spark's connection is set to auto-join on your phone.

Hi Kloo Gee
Your absolutely correct the WiFi will not connect if already connected to another hotspot. Not a problem for most places I take photos. In fact DJI have fixed most of the issues with Sparks firmware and GO 4 App and expect the QR code not recording hotspots for auto connection will soon be updated.
It's very impressive how they have worked on improving all the software, even if GO  4 APP did cost me my first Spark. Because a Spark is out-of-sight from about 70m, its much more reliant on coms than larger Drones. The UAVs I have made myself are much larger than Spark and I have never lost sight of them. So what makes me a fan of this little drone has also caused me some angst.

Thanks everyone for responding to my problem. I greatly appreciate the help. It shows what great people most drone enthusiasts are.