Why can't I rollback from W10 Mobile to 8.1 Lumia 640 XL?

[Windows Central Question]

Can't rollback from w10 mobile to 8.1 Lumia 640 XL

I've tried few time but it just won't install 8.1 on my lumia using windows device recovery tool. and one more question: does recovery tool rollsback to 8.1 or 8.1 update 2?

 

[colinkiama]

Re: Can't rollback from w10 mobile to 8.1 Lumia 640 XL

Try installing the drivers for it by plugging the phone in with the recovery tool closed then try again.

Also, it will go back to the latest stable consumer release which is 8.1 update to for the 640.

 

[emperor_skull]

Re: Can't rollback from w10 mobile to 8.1 Lumia 640 XL

The recovery tool won't install, keeps showing hash value is not correct error code any solution?