You need to rebuild c++utilities first.
You're not the first user to run into this problem. I'm really wondering why you would assume it makes sense to (re)build syncthingtray before its dependency c++utilities. If you're using an AUR helper you should likely move to using a better one or report a bug. However, I suggest to simply run makepkg/makechrootpkg manually and read various Wiki pages to understand how package building works. If you're lazy, I also provide a binary repository (see pinned comment).
Pinned Comments
Martchus commented on 2016-10-31 11:39 (UTC) (edited on 2022-01-11 11:30 (UTC) by Martchus)
All my packages are managed at GitHub where you can also contribute directly: https://github.com/Martchus/PKGBUILDs
There also exist a binary repository: https://wiki.archlinux.org/index.php/Unofficial_user_repositories#ownstuff
The packages within the binary repository are built against the latest packages from Arch Linux and hence might not be compatible with Manjaro. This can be the cause when the Plasmoid doesn't work.
Like with any other package a rebuild is required when the soname of a dependency like boost changes (see e.g. https://github.com/Martchus/syncthingtray/issues/98). The package in my binary repository should be rebuilt in a timely manner. I'm usually also updating
pkgrel
of the AUR package when a rebuild is required (only in accordance with Arch Linux of course, not in accordance with Manjaro).Note that the tests of this package might fail despite there's nothing wrong (e. g. because Syncthing is just too slow and the test runs in a timeout). To ignore those false-positives, build the package with
makepkg --nocheck
ormakechrootpkg -- --nocheck
. It makes still sense to report failures. But please include the actual error message and not just the last few lines.