Technical Tip: FortiAuthenticator showing 'Wrong Image for this model' when attempting to perform TFTP reimage

[jstan]

Description	This article describes how to fix the error 'Wrong image for this model' when attempting to perform a TFTP reimage.
Scope	FortiAuthenticator version 6.1.1. FortiAuthenticator version 6.4.0.
Solution	1) When attempting a TFTP reimaging on FortiAuthenticator v6.1.1 and above (Below 6.4.0), it is possible to observe the error 'Wrong image for this model' even when the image model is correct and passed the md5 integrity check. 2) For the affected firmware, performing TFTP re-imaging using the firmware downloaded from the support portal is not possible, it will only be possible to perform an upgrade using the image downloaded. 3) In order to perform a TFTP transfer, it is necessary to open a TAC ticket and request a special debug image (Based off 6.1.1) from Fortinet TAC and upgrade to the desired firmware (Alternatively, it is possible to install version 6.4.0 or above to avoid this issue).