Why do I get an error saying Web Importer extension is corrupted on Firefox?

When Firefox Content Blocking is set to "Strict: Stronger protection, may cause some sites to break", the Firefox Web Importer install process breaks.

In particular:

• The install page https://www.mendeley.com/reference-management/web-importer will not render properly.
• When trying to install the Web Importer, an error message will display that 'The add-on downloaded from this site could not be installed because it appears to be corrupt'.

To fix the issue:

1. Type about:preferences into the Firefox URL bar.
2. Click 'Privacy & Security'.
3. Select 'Standard'.

Mendeley Web Importer also requires third-party cookies in order to complete the sign-in process via id.elsevier.com, so it is advised to keep the settings on 'Standard' rather than 'Strict' when using Mendeley Web Importer.