vCenter Converter 6.0 is the last release that support Acronis images, see: https://www.vmware.com/support/converter/doc/conv_sa_60_rel_notes.html#interop
VMware vCenter Converter Standalone 6.0 Support Notice
VMware vCenter Converter Standalone 6.0 is the last release of the product to support third-party backup images and virtual machines as sources for conversion. This capability will be discontinued in the next release. If you use this capability, you should start planning your transition.