https://www.freebsd.org/releases/10.3R/installation.html#upgrade-source says --- The procedure for doing a source code based update is described in and . --- The relevant links that are obviously meant to be there at the end of the sentence are missing.
Thank you for sending us the report about the missing links. Unfortunately, the link you provided is part of the release installation documentation, which can not be changed after the release is done. If you want to know how to update FreeBSD, you can find the information in the "Updating and Upgrading FreeBSD" chapter of the handbook: https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/updating-upgrading.html We also have the german version available as a translation if you prefer: https://www.freebsd.org/doc/de_DE.ISO8859-1/books/handbook/updating-upgrading.html If you have further questions about the upgrade process, you can post questions on the freebsd mailing-lists, forums or open another PR in case you experience a specific problem. You can also contact me directly if you prefer.