Data processing apparatus, image processing apparatus and method for verifying and restoring operating system in activation mode

A data processing apparatus comprising:

• a storage unit that stores a first operating system (OS), a first application program executed after the first OS is executed, a second OS, and a second application program executed after the second OS is executed;
• and
• at least one processor configured to, in a first activation mode, verify the first OS, execute the verified first OS, and then execute the first application program, and, in a second activation mode, execute the second OS, and then execute the second application program,
• wherein the at least one processor is further configured to restore the first OS, in a case where it is determined on the verification of the first OS that the first OS is not valid, by overwriting at least a part of the first OS which is not valid with at least part of the second OS.