Ever seen this error in Sitecore?
I have seen this all too often…. even when I haven’t cancelled the installation.
I always thought it was an error with my instance….and ended up installing the package via another means (Sitecore Rocks).
Mike Edwards quickly mentioned the issue to me when I was screen sharing with him about some other issue, and this came up. It was one of those ‘I can’t believe I didn’t know that’ moments.
Turns out the error is shown when files are being overwritten, and a popup window is attempted to be shown by Sitecore to allow you to overwrite the file.
If popups are blocked in the browser, the installation fails with this error.
I never knew this because sometimes the popup blocker notification isn’t shown very obviously in Chrome (see image below).
To fix this, click on the popup blocker notification to the right of the address bar, and allow popups.
Then reinstall the package, and you’re good to go.