Many of Apple's signed packages - which are part of Software Update Filesets - are due to expire on the 24th October 2019. Any that have this expiry date will fail to instal after this date, perhaps with a message suggesting they are damaged.
Please note that this also affects most anything downloaded from Apple's website , such as iTunes installers and so on.
PKG installers for macOS , supplied by Apple, are signed with a certificate. This certificate is due to expire soon. To check the expiry of a PKG certificate :
- Export the PKG file from a Fileset
- Launch the PKG
- At the introduction page to the installer, click on the padlock in the top right corner
- The installer should display the certificate
Apple choose which packages they wish to re-sign. Therefore some packages may not work after this date and there may not be an updated version from Apple. Either Apple have chosen to deprecate the package or they have overlooked the package. If it is considered the later is the case, a request to Apple should be required to address the package in question.
Any package already within a Fileset, with an expiry for this date, will require removal and re-download from Apple.