Xsendfile options in Configuration Manager are untouched.
Binary download - images look just fine. Display perfectly in Firefox from an .html page with <img> tags, created in the same directory as doku.php.
I use the DokuWiki syntax page as my test; dokuwiki-128.png is supposed to appear several times on that page. The images appeared when DokuWiki was first installed; now they no longer appear. Right click where the image should be, display in new tab, get the detail page for the image but the image is not displayed, just a link. Interesting - on reload of this detail page, Firefox briefly displays a broken image box in place of the link, then immediately it goes away and is replaced by the link.
While setting up DokuWiki in a local development environment (EasyPHP on XP), this problem happened again. The syntax page images were displayed at first, now they're not displayed anymore. Clearing browser cache, /data/cache, forcing the page to reload, nothing helps.
While researching this problem I came across a Mozilla bug report for the same message (cannot be displayed... contains errors). Nothing was wrong with the images they used to test. It was a caching problem with the browser, which was fixed (quite awhile ago). They followed a very methodical process to narrow down and reproduce the problem. FWIW:
https://bugzilla.mozilla.org/show_bug.cgi?id=121084. A brief description:
Sometimes images aren't displayed on their prospective pages, and when I right click on the image and go to "display image" it gives me a message with the following error message.
- The image "[image name]" cannot be displayed because it contains errors. What can I do?
This is a known bug that is being worked on. The image itself is fine, i.e. it contains no errors.
The reason for this behavior appears to be the fact that Mozilla - depending on your Cache settings - requests the image twice. It only appears on websites that do not allow images to be linked to/called directly from outside of their pages. Since Mozilla does not send the referrer (i.e. web address of the page where the file is linked from) the second time it requests the image, the website sends an "access denied" page in HTML form where Mozilla is expecting an image, hence the error messsage (Mozilla tries to display an image when it receives an HTML page, so for the browser, the "image" contains an error). Solution: Change your cache settings to "Compare the page in the cache to the page on the network When the page is out of date". To do so, select "Edit" -> "Preferences" -> "Advanced" -> "Cache".
Makes me wonder if DokuWiki is doing something similar?
I've spent days trying to figure this out. I initially liked DokuWiki. Now I'm about ready to give it up. It's just not worth this much of my time, and trying to find an answer or even a path to follow to debug this in the manual or the forums seems more difficult than it should be.