vSphere upgrade 5.5 U1 to 6.5 U1

Hello Expert

Customer has vSphere 5.5 U1 and they are wishing to upgrade it to vsphere 6.5 U1. Will the in-place upgrade supported by VMware , for example if we put vsphere 6.5 U1 cd/dvd on the ESXi 5.5 U1 blade and straightaway we can upgrade?? If you can share kb links will be appreciated.

Thanks

Bala