We have created a workaround to address the issue and have submitted it to the edge store. The workaround is currently being reviewed by Microsoft and should be available soon.

The Microsoft Edge browser has updated causing an issue with the Read&Write for Microsoft Edge Add on being unable to open. Microsoft is investigating a fix to address this issue effecting many other extensions as well as Read&Write. Our development team is also working to restore functionality as soon as possible pending a fix.

We will update you here once functionality is restored.