I have just stumbled across some behavior that looks weird to me.
There is a small static test page on my webserver that has the following code:
<html>
<body>
<a href="ftp://my-ftp-server/t.jpg">
<img src="ftp://my-ftp-server/t.jpg"/></a>
<br>image
</body>
</html>
When I load the page in Firefox 51, the image on the page is shown as broken. In the standard Firefox developer console I do not see any requests (well, it is an FTP request, so not surprising it is not shown in HTTP requests list).
When I click on the image box, the image loads correctly.
What I checked so far:
- Both links are identical.
- The page opens in Google Chrome 56 correctly.
- When I change the image data link from ftp to http (the ftp server is accessible via http) the page loads correctly in Firefox.
- This does not seem to be a caching issue (clearing the cache does not resolve it)
- There is no AdBlock or similar add-ons installed.
- Developer console shows "Could not load the" tooltip when mouse hovers over the image link.
What could be the reason for Firefox 51 not displaying the image with data accessible via FTP?
Details: This is Mozilla Firefox 51.0.1 built for OpenSUSE Leap 42.1. So far I could not reproduce neither on Google Chrome, nor on Firefox 50.1.0.