Folks you are not going to like this...
I have just spent a desperate weekend trying to solve this problem. My Nokia 820 had connected flawlessly with every computer I have used (many) until it installed Cyan update to 8.1. Now I get the mentioned USB device error. At the moment the best each computer can do is think that the phone is a Bluetooth device. I have done all the standard procedures. Rebooted everything, changed cables, deleted device settings, reinstalled the PC app (win 8 computer) and program (win 7 computer).
I have downloaded the recommended winUSB and tried to do a manual device update.
What is wrong with most people's suggestions about this problem that they assume the phone appears in the device manager. It doesn't, well it no longer does correctly. It doesn't appear in Portable area as would be expected. It will appear in the other devices as an Unknown Device.
When following the method of telling the unknown device that it is a usb device and selecting winUSB it rejects it as a device can't start. I tried all the different device drivers in the portable section and the usb devices section.
I saw that one recommendation was to remove the SD card so I did that. Nothing. The phone would charge off the computer cable, it just wouldn't recognize it properly.
As I say, you are not going to like what I discovered has fixed it. A pin!!! Repeated use had build a fine layer of lint inside the usb socket on the phone. I started scratching around in the hole and pulled out much more stuff than I could see or image. I believe what has happened is that that had built up at the bottom of the socket such that the plug can't quite push in far enough to get the data connection even though the power gets through. The update was just a distracting coincidence. I did also scrape the contacts in the socket carefully which may have also helped. Be gentle with your pin - don't snap the contacts or you're dead. Pay attention to the bottom of the socket. If your pin is too fat to fit down the narrow side of the socket, don't force it, just go find a needle instead!
2 minutes cleaning and my phone and computer love each other again. :-) Interestingly now I can also see that the plug pushes in further.
Hope that helps you all.
I have just spent a desperate weekend trying to solve this problem. My Nokia 820 had connected flawlessly with every computer I have used (many) until it installed Cyan update to 8.1. Now I get the mentioned USB device error. At the moment the best each computer can do is think that the phone is a Bluetooth device. I have done all the standard procedures. Rebooted everything, changed cables, deleted device settings, reinstalled the PC app (win 8 computer) and program (win 7 computer).
I have downloaded the recommended winUSB and tried to do a manual device update.
What is wrong with most people's suggestions about this problem that they assume the phone appears in the device manager. It doesn't, well it no longer does correctly. It doesn't appear in Portable area as would be expected. It will appear in the other devices as an Unknown Device.
When following the method of telling the unknown device that it is a usb device and selecting winUSB it rejects it as a device can't start. I tried all the different device drivers in the portable section and the usb devices section.
I saw that one recommendation was to remove the SD card so I did that. Nothing. The phone would charge off the computer cable, it just wouldn't recognize it properly.
As I say, you are not going to like what I discovered has fixed it. A pin!!! Repeated use had build a fine layer of lint inside the usb socket on the phone. I started scratching around in the hole and pulled out much more stuff than I could see or image. I believe what has happened is that that had built up at the bottom of the socket such that the plug can't quite push in far enough to get the data connection even though the power gets through. The update was just a distracting coincidence. I did also scrape the contacts in the socket carefully which may have also helped. Be gentle with your pin - don't snap the contacts or you're dead. Pay attention to the bottom of the socket. If your pin is too fat to fit down the narrow side of the socket, don't force it, just go find a needle instead!
2 minutes cleaning and my phone and computer love each other again. :-) Interestingly now I can also see that the plug pushes in further.
Hope that helps you all.