Go to the re-upload form for file [[File:Insigne de l'ETAP.jpg]] on the Commons:

http://commons.wikimedia.org/w/index.php?title=Special:Upload&wpDestFile=Insigne_de_l%27ETAP.jpg&wpForReUpload=1

The XHTML is invalid, it contains

<input tabindex='2' type='hidden' name='wpDestFile' id='wpDestFile'
value='Insigne_de_l'ETAP.jpg' /><tt>Insigne_de_l'ETAP.jpg</tt>

'Insigne_de_l'ETAP.jpg' is not a valid string.

As a result, you cannot upload a file, the server will always respond
"The file has no extension (like ".jpg")." (At least in Firefox, because
FF passes "Insigne_de_l" as the value and ignores the rest.)

Somehow, the single quote in the file name does not get escaped.

See also http://commons.wikimedia.org/wiki/Commons:Bistro#Pb_de_t.C3.A9l.C3.A9chargement_d.27une_nouvelle_version

Version: unspecified
Severity: normal
URL: http://commons.wikimedia.org/w/index.php?title=Special:Upload&wpDestFile=Insigne_de_l%27ETAP.jpg&wpForReUpload=1