Gefunden: C:\Users\*\AppData\Roaming\Mozilla\Firefox\Profiles*.default\mimeTypes.rdf
Aber dort steht nichts von image/jpeg
Lösung gefunden dort:
Registrierungseintrag bei Windows 10 ist der Schuldige:
HKCR\MIME\Database\Content Type\image/jpeg
Von .jfif in .jpg
Code
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\MIME\Database\Content Type\image/jpeg]
"AutoplayContentTypeHandler"="PicturesContentHandler"
"CLSID"="{25336920-03F9-11cf-8FD0-00AA00686F13}"
"Extension"=".jfif"
"Image Filter CLSID"="{607fd4e8-0a03-11d1-ab1d-00c04fc9b304}"
[HKEY_CLASSES_ROOT\MIME\Database\Content Type\image/jpeg\Bits]
"0"=hex:02,00,00,00,ff,ff,ff,d8Code
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\MIME\Database\Content Type\image/jpeg]
"AutoplayContentTypeHandler"="PicturesContentHandler"
"CLSID"="{25336920-03F9-11cf-8FD0-00AA00686F13}"
"Extension"=".jpg"
"Image Filter CLSID"="{607fd4e8-0a03-11d1-ab1d-00c04fc9b304}"
[HKEY_CLASSES_ROOT\MIME\Database\Content Type\image/jpeg\Bits]
"0"=hex:02,00,00,00,ff,ff,ff,d8Gruss Urbauer