Now the packages are held in an instance of MyGet and they were removed, but I expected it to not find the package and just carry on with the cache, not error.
Thanks for getting in touch and I’m sorry you are having these issues.
The package cache for external feeds are stored (by default) for 20 days (and the file hasn’t been accessed for the last 3 hours of the scheduled cleaner task run), so in this case I assume that the package used here had been removed from the package cache unfortunately.
You can change the number of days packages from external feeds are kept in the package cache by using the Octopus.Server.exe configure --cachePackages <DaysToKeepPackagesInCache> command.
My sincere apologies for the inconvenience caused by this.