[Sumukh Phalle1992]

On my windows 10 pc, it's showing error "The last USB device you connected to this computer malfunctioned, and Windows does not recognize it.".
Well i haven't got Technical Preview on my laptop but my phone L640XL having Technical Preview. Other windows phones (non TP) are able to connect but only my phone isn't connecting. Many USB cables tried but error is same.
On my laptop all drivers are up-to-date. So i think the problem is with my phone. Please help to solve this problem.

[Sumukh Phalle1992]

Also it's showing "device charging slowly" error on phone

[ads13]

Replug the usb data cable.
Or
Attach USB cable direct to the usb slot.(in case of using USB hub)

[Sumukh Phalle1992]

I tried it but nothing happened...

[ads13]

Also it's showing "device charging slowly" error on phone

It's because you have to use your original charger
or
using old model of USB data cable(whether its Nokia made)

[Sumukh Phalle1992]

I connected L520 with same cable.. L520 added successfully.. So no matters which cable i connect..

[ads13]

I tried it but nothing happened...

Use another USB cable.
Or
Use card reader
Or
If it isn't work then use Shareit. Or Easy transfer (works with Wi-Fi connection)

[Sumukh Phalle1992]

Just connected L535 and it's also working.. I think the problem is with L640XL (Technical Preview) updated.

[ads13]

I connected L520 with same cable.. L520 added successfully.. So no matters which cable i connect..

It matters for sometimes. You have to try another one USB cable.

[Sumukh Phalle1992]

Dude, i have tried nearly 4-5 usb cables.. Is there problem with current build 10.0.10586.36?

[ads13]

Just connected L535 and it's also working.. I think the problem is with L640XL (Technical Preview) updated.

I'm not sure but the main reason is your phone's model which isn't compatible with your usb cable.

[ads13]

Dude, i have tried nearly 4-5 usb cables.. Is there problem with current build 10.0.10586.36?

Hope so. That's why I haven't use win10m yet.

I suggest you to downgrade your mobile OS to 8.1

[Sumukh Phalle1992]

Well downgrading to W8.1 is not possible.. Anyway Thanks!

[ads13]

Well downgrading to W8.1 is not possible.. Anyway Thanks!

http://forums.windowscentral.com/e?l...token=wgdtEoIe

[Sumukh Phalle1992]

Above link is not active..

[ajayden]

Above link is not active..

Since you have tried all the options mentioned in the posts above, just soft reset your phone and connect to the computer.

If it still does not connect, then try to hard reset your phone and then connect.

[Sumukh Phalle1992]

Since you have tried all the options mentioned in the posts above, just soft reset your phone and connect to the computer.

If it still does not connect, then try to hard reset your phone and then connect.

[Sumukh Phalle1992]

When i plugged my phone to pc, (in device manager>Universal Serial Bus controllers>Unknown device). This "unknown device" is visible for only 1-2 sec and after it hides. But after my quick clicks, i was managed to check properties. Then i found this, "Unknown USB Device (Device Descriptor Request Failed) Properties".
Is there any solution except "Hard Reset"?

[RumoredNow]

Try this utility on your PC: View any installed/connected USB device on your system

Right click the .exe and Run as Admin. Then delete any USB drivers marked for Nokia or Lumia. Now plug the phone in and let a fresh instance for drivers install.

[Sumukh Phalle1992]

Not working! Neither Hard reset nor above procedure...
Now checking sd card for errors.. Hope this will work..

[ads13]

Go to MS reseller then.

[Sumukh Phalle1992]

Can I solve it by MS-DOS or any app?

[ads13]

If you are using win10 mobile then Again I suggest you to get back to windows 8.1 by
First, leave the insider program.
Use Windows device Recovery tool to get back to stock version.

Link - http://wmpoweruser.com/how-to-roll-b...ows-10-mobile/

[ajayden]

Not working! Neither Hard reset nor above procedure...
Now checking sd card for errors.. Hope this will work..

Also it might be an issue where the mini USB port on the phone is damaged. You need to bring to a service center to check. Before going to the service center, try to downgrade to 8.1 and check if it works.

[Sumukh Phalle1992]

A sec before i decided to rollback to 8.1 but the main problem is, for rollback my phone should be connected to PC! And this is not possible. Because my phone doesn't detect on PC. So rollback will not work.
Now i think, I have to wait for next update.