What does dfu mode do

As its full name— Device Firmware Update Mode— suggests, the mode is used to update the actual firmware of the device, mostly to install a boot loader. DFU Mode is hard to enter, requiring convoluted sequences of button presses to enter. Even when you reach DFU Mode, the screen remains blank. Unlike recovery mode, which can be updated with a software update, DFU is burned into the hardware, and cannot be altered. There are two good uses for DFU Mode. One is to repair an iPhone or iPad that has a corrupt bootloader.

For instance, if you are running a beta of a new version of iOS, you cannot downgrade through a Settings toggle or hooking up to a computer. These days, Apple stops signing iOS versions very soon after updates are released, so you have a short window to downgrade. DFU mode was also an essential part of jailbreaking. While some early jailbreaks involved little more than clicking on a link, many of them required DFU Mode. That door was closed in iOS 6, but resurfaced with the checkm8 jailbreak for older iPhones.

The procedure for entering DFU Mode varies with each new series of iOS devices, but involves pressing the right hardware buttons in the right order, usually for an exact number of seconds.

Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Sam Costello. Sam Costello has been writing about tech since His writing has appeared in publications such as CNN.

Facebook Twitter. Updated on December 10, Tweet Share Email. In This Article. If the iTunes logo and message appear, you held the button for too long and need to start again. Was this page helpful? Thanks for letting us know! Email Address Sign up There was an error. Please try again. You're in! Thanks for signing up. If you just want to go to recovery mode, skip the second hold on both buttons and simply connect the phone while holding down Home , then wait for 'Connect to iTunes' screen on the phone.

Click OK. You're now in DFU mode. All products recommended by Engadget are selected by our editorial team, independent of our parent company. Some of our stories include affiliate links. If you buy something through one of these links, we may earn an affiliate commission. Researchers identify 'cybermercenary' group behind dozens of hacks. Sony reportedly cuts PS5 production again as chip shortages and shipment issues bite.