“optipng” cannot be opened because the developer cannot be verified.

[zhrance]

Title says it all, did some Googling but can't find a clear answer.

[timohofmeijer]

I had same issue when I installed it by downloading and double clicking the downloaded plugin from the download folder. I uninstalled it and installed it again via Sketch Runner, which resolved the issue.

[ghs]

Same here but for jpegoptim

Never happened before but after the latest macos update.