You can let the addon author know about this problem so they can update the addon before drop and drag stops working on a future version.

Most author contact information is on their website or the addons's page on AMO.

I too have the problem: W7 64 bit. Drag and drop worked until yesterday when I "upgraded" to FF v 26.0 - I can no longer drag passwords etc from my password manager to website fields - a barred circle appears when I try to drag.

I tried pressing ESC (one profferred solution) and also reset FF to no avail.

This is more than annoying: some of my passwords are dozens of characters long and there's no way I can access sites by typing them in! I need a solution, even if it's reverting to a previous version.

Further to the above - I had to reboot this morning for another reason - and drag 'n drop now works in FF!

One -or both - of the solutions I tried yesterday must have required a reboot, not just a FF restart.