The problem of DjVu thumbnails are not being generated at all

is still hitting us. The thumbnails of DJVU files are shown as 0x0 pixels more often than not. We created a test environment so .php?title=File:Provinz_Rheinland_1888.djvu is available at 2025-02-19 for a while to inspect the problem

As @tgr pointed out we inspected the logfiles after doing

Processing next 18 row(s) starting with 200Jahre-Pfarrgemeinde_St-Agatha-Straberg.djvu.
Refreshed File:200Jahre-Pfarrgemeinde_St-Agatha-Straberg.djvu.
Refreshed File:Provinz_Rheinland_1888.djvu.

Finished refreshing file metadata for 18 files. 2 needed to be refreshed, 16 did not need to be but were refreshed anyways, and 0 refreshes were suspicious.

and the log file now shows:

[Mime] MimeAnalyzer::doGuessMimeType: analyzing head and tail of /var/www/html/images/4/46/Provinz_Rheinland_1888.djvu for magic numbers.
DjVuImage::getMultiPageInfo: skipping 'DIRM' chunk
DjVuImage::getMultiPageInfo: multi-page DJVU file contained no pages
[Mime] MimeAnalyzer::guessMimeType: internal type detection failed for /var/www/html/images/4/46/Provinz_Rheinland_1888.djvu (.)...
[Mime] MimeAnalyzer::detectMimeType: magic mime type of /var/www/html/images/4/46/Provinz_Rheinland_1888.djvu: image/vnd.djvu
[Mime] MimeAnalyzer::guessMimeType: guessed mime type of /var/www/html/images/4/46/Provinz_Rheinland_1888.djvu: image/vnd.djvu
[Mime] MimeAnalyzer::improveTypeFromExtension: improved mime type for .djvu: image/vnd.djvu
Getting DjVu metadata for /var/www/html/images/4/46/Provinz_Rheinland_1888.djvu
DjVuImage::getMultiPageInfo: skipping 'DIRM' chunk
DjVuImage::getMultiPageInfo: multi-page DJVU file contained no pages

the last message is very suspicious since

wget //4/46/Provinz_Rheinland_1888.djvu
djvudump Provinz_Rheinland_1888.djvu 
  FORM:DJVM [1006] 
    DIRM [994]        Document directory (indirect, 196 files 178 pages)
      Provinz_Rheinland_1888_010_0001.djbz -> Provinz_Rheinland_1888_010_0001.djbz
...
      Provinz_Rheinland_1888_346_0001.djvu -> Provinz_Rheinland_1888_346_0001.djvu

and

root@6bbd81b5735a:/var/www/html/images/4/46# ls -l | head -4
total 34552
-rw-r--r-- 1 www-data www-data   1018 Feb 19 07:11 Provinz_Rheinland_1888.djvu
-rwxr-xr-x 1 www-data www-data  59795 May  4  2009 Provinz_Rheinland_1888_000_0001.djvu
-rwxr-xr-x 1 www-data www-data  58166 May  4  2009 Provinz_Rheinland_1888_000b_0001.djvu

What can we do to get back proper djvu behavior?

See .php?title=File:Alice_in_Wonderland.djvu for the official example and how the behavior should be.