I just updated TB to the lattest version 52.1.1
I had working addon (ContactsSidebar) in my TB, but after updating it it doesn't show and gives me an error:
XML Parsing Error: undefined entityLocation: chrome://contactssidebar/content/contactsPanel.xul
Line Number 210, Column 9:        <label value="&searchInput.label;"/> 
What can do about it? Is there a solution?