It was already possible to update your F25 templates to F26, but fresh F26 templates are now also available to install. (Both normal and minimal)
https://ftp.qubes-os.org/repo/yum/r3.2/templates-itl/rpm/

With F27 released, F25 will go EOL after a few weeks so it is advised to update.

The fresh F26 template gives errors on updating:
 Problem 1: package salt-2017.7.2-1.fc26.noarch requires dnf-utils, but none of the providers can be installed
  - package dnf-utils-2.1.5-1.fc26.noarch conflicts with yum-utils < 1.1.31-513 provided by yum-utils-1.1.31-512.fc26.noarch
  - package dnf-utils-2.1.1-1.fc26.noarch conflicts with yum-utils < 1.1.31-513 provided by yum-utils-1.1.31-512.fc26.noarch
  - cannot install the best update candidate for package yum-utils-1.1.31-512.fc26.noarch
  - cannot install the best update candidate for package salt-2016.11.5-3.fc26.noarch
 Problem 2: problem with installed package yum-utils-1.1.31-512.fc26.noarch
  - package dnf-utils-2.1.5-1.fc26.noarch conflicts with yum-utils < 1.1.31-513 provided by yum-utils-1.1.31-512.fc26.noarch
  - package salt-2017.7.2-1.fc26.noarch requires dnf-utils, but none of the providers can be installed
  - package dnf-utils-2.1.1-1.fc26.noarch requires dnf-plugins-core = 2.1.1-1.fc26, but none of the providers can be installed
  - package salt-ssh-2017.7.2-1.fc26.noarch requires salt = 2017.7.2-1.fc26, but none of the providers can be installed
  - cannot install both dnf-plugins-core-2.1.1-1.fc26.noarch and dnf-plugins-core-2.1.5-1.fc26.noarch
  - cannot install the best update candidate for package salt-ssh-2016.11.5-3.fc26.noarch
  - cannot install the best update candidate for package dnf-plugins-core-2.1.5-1.fc26.noarch

You have to do only once: dnf update --best --allowerasing .There is some conflicting packages requirements between F25 and F26. Also, if you encounter problem with pulseaudio you have to enable current-testing (see https://groups.google.com/d/msg/qubes-users/o5aWFKvz8-g/bCOTbqQ3BAAJ) until some packages will be pushed in current.

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Lorenzo Lamas:

> It was already possible to update your F25 templates to F26, but
> fresh F26 templates are now also available to install. (Both normal
> and minimal)

Just a heads up, to use that version of the _minimal_ template (i.e
201711170336) as a NetVM/ProxyVM, you'll have to manually install the
iptables package. Or wait just a little longer for probably the next
qubes-core-vm (r3.2) or qubes-core-agent-networking (r4.0) update.

https://github.com/QubesOS/qubes-core-agent-linux/pull/73
https://github.com/QubesOS/qubes-core-agent-linux/pull/74

Rusty
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