Open With Adobe PDF Reader 2.0.0 has been blocked for your protection.

Why was it blocked?
Version 2.0.0 shipped with a hidden coin miner, which degrades performance in users who have it enabled. Version 1.2.3 currently available on AMO is not affected.
What does this mean?

The problematic add-on or plugin will be automatically disabled and no longer usable.

When Mozilla becomes aware of add-ons, plugins, or other third-party software that seriously compromises Firefox security, stability, or performance and meets certain criteria, the software may be blocked from general use. For more information, please read this support article.