AddThis is no longer running, they have put an annoucement in their website.
“As part of a periodic product portfolio review, Oracle has made the business decision to terminate all AddThis services effective as of May 31, 2023.” https://www.addthis.com/
So the AddThis plugin doesn’t work in OJS. We have delated the plugin in our multi website to avoid confusion.
I am not sure if this is the right way to inform the community or if there have been another post warning about it.
Hi @RCUB,
Thanks for your post. PKP was made aware of this some time ago: Notice of Termination of AddThis Services · Issue #28 · pkp/addThis · GitHub
We are looking into whether or not we make a more formal announcement about this in the future?
-Roger
PKP. Team
Thanks @rcgillis , I looked for this information in the forum but I could not find it. Sorry for opening a new post about it.
For future references, as Diego explains in gitHub, Shariff is the natural substitute for AddThis.
And while we’re on the subject, it turns out that it’s a much better choice in terms of privacy… so all good news. 
That’s great news Marc!
Thank you for sharing this information!
Just noticed the Shariff plugin is only shown in 3.3+ plugin galleries.
If you are in 3.2, you will probably like to know you can install it manually from Ronald’s releases: Releases · ojsde/shariff · GitHub
For 3.2 here you have a direct link:
https://github.com/ojsde/shariff/releases/download/v3_1_2/shariff-3.1.2.zip
I qualsevol cosa, xiula
Salut,
m.
That’s super wonderful and super thoughtful of you! 
Thank you very much, I am going to install it for sure!
Moltes gràcies Marc, estàs en tot!