Towards the end of December, the MacOS App Store notified me of an update for the Day One app. Every attempt I made to install the update failed. On both of my MacBooks. I made sure to quit the Day One app and the Day One menu bar extension, but every attempt to run the update failed without any kind of error message.
I emailed support, and they suggested making sure DOWidgetExtension was stopped in Activity Monitor. I had to Force Quit the process, but doing so finally allowed the update to install successfully.
I couldn’t find anything on Google about this, so I thought I’d post it just in case someone else was having the same issue. Clearly it’s not a wide spread issue, but if it’s a problem for you, give this solution a try.
Much thanks to Adam at Day One for the suggestion.