Download Internet Download Manager 6.11 build 8 Full version and enjoy compatibility with latest Firefox and any other web browser.
Simply download this .zip file and extract this. Then open installation guide.
Please note that if you have already any old version of IDM then re-install the IDM. Please then exit idm icon from task bar (right bottom, near time clock) and then Run Patch after installing and locate IDMan from C:/Program File/Internet Download Manager and then open this and Enjoy the full version of IDM 6.11 Build 8.