In T296912#7578757, @Inductiveload wrote:

It occurs to me that if the Google server is hitting the API for an image that isn't rendered, if it's using a default user agent, it would get a 403 telling it to set a user agent. And it wouldn't be too unreasonable to cache that failure for a bit as they might want to avoid hammering a server that's apparently not interested.

Hitting the image thumbnail URL might seem safe because the user has already loaded it to view the page, but the next page result is also pre-fetched, so it's actually quite possible for Google to be hitting uncached images.

I had not seen that you had reported the same problem, ( i reported https://phabricator.wikimedia.org/T270928) Results that the user Fæ (BOT?) was loaded pdf files from Internet Archive https://commons.wikimedia.org/wiki/Special:Contributions/F%C3%A6 and so blocks djvu upload with this tool, ignoring that pdf version are poor version that djvu files. Djvu files are priority for Wikisource for OCR amd transcripts.

Thanks! @Dereckson, work fine all namespace!

See https://es.wikisource.org/wiki/Categor%C3%ADa:Portales_a_mejorar , previous Portal prefix problems, Portal:Argentina --> :Argentina

Revert PLEASE! This change https://gerrit.wikimedia.org/r/#/c/352250/2/wmf-config/InitialiseSettings.php IS WRONG. Like said Ninovolador, namespace 104 assigned to Index namespace, this change has caused a bug with indexes of books.