Syncthing 0.12.23’s upgrade mechanism had an incorrect limit on the size of responses received from GitHub’s API, which is used for determining if an update is available. This meant that version 0.12.23 was not able to upgrade, because it thought it was receiving too much information from GitHub.
The API response from GitHub contained everything on the “Releases” page, including all past releases and their associated changelogs. In order to un-break users on 0.12.23, the size of this response had to be reduced. This required removing records of previous releases, which also required removing their changelogs.
I should add, the upgrade mechanism has now been changed slightly, so that this situation shouldn’t happen again.
The problems is to understand where 0.12.15 commits start, and commit log is also too verbose. Changelog can be skimmed, and commit messages are hard to skip - need to scroll through all these pages. Detailed changelog may be not as useful as human friendly summary.