when i try to login windows 8.1 store then this error is appear ( bad length )

Why can't I sign in to the Windows Store?

Hi Bhatti,

In addition to what has been suggested by MVP S.Sengupta.

You could navigate to Charms Bar->Settings->Change PC Settings->Accounts.

From there, you will see your account, and the option to disconnect. After that, reboot, repeat above, but choose connect to Microsoft Account.

Also you could try refresh your system.

http://windows.microsoft.com/en-us/windows-8/restore-refresh-reset-pc

Regards,

D. Wu