JabRef version

5.4 (latest release)

Operating system

Windows

Details on version and operating system

Windows 10 Pro Version 21H1

Checked with the latest development build

• I made a backup of my libraries before testing the latest development version.
• I have tested the latest development version and the problem persists

Steps to reproduce the behaviour

1. For 5.4 only (not earlier): Prepare one or more links in a 'file' field, one of which is type URL
2. Almost any string is OK for the URL entry (with backslashes before colons) except (drumroll)...
3. ... putting "www." in front of a site name, which still happens pretty often in the World Wide Web... :)
   E.g., "https\://bogus.org" works fine, "https\://www.bogus.org" makes it look like all linked files disappeared.

Before and after images:

No "www." prefix:

"www." prefix added:

Appendix

...

Paste an excerpt of your log file here