Revert my phone to htc system software

[AC Question]

I am not able to update my phone to the htc updated software . Getting an message " we have determined that your phone may be running a modified version of its system software for your protection we cannot we cannot update your phone please revert your phone to the official htc system software to update your phone

 

[B. Diddy]

Welcome to Android Central! Which HTC phone? Was it ever rooted?

 

[Golandaz]

My phone is htc desire 826.. no its not rooted

 

[B. Diddy]

Did you buy the phone brand new from a wireless carrier, or did you buy it used or refurbished? If you got it from some reseller, it's always possible that the previous owner rooted it.