SUMMARY Clicking on trusted links in email messages results in Error code 100: Unknown error code 100 Could not find the program '/usr/bin/_neon.firefox' Please send a full bug report at https://bugs.kde.org. STEPS TO REPRODUCE 1. 2. 3. OBSERVED RESULT EXPECTED RESULT SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: KDE Frameworks Version: Qt Version: ADDITIONAL INFORMATION
I'm seeing this as well, also occurs when clicking on a .html file in Dolphin.
After upgrading to focal 20.05 with Plasma 5.19.5 I am having the same issue. KIO attempts to open the browser by executing '/usr/bin/_neon.firefox' which does not exists. The symlink in actually is '/usr/bin/firefox'. This results in the error reported here. This is reproducible in Element (matrix client), kmail, dolphin.
The problem can be solved by manually switching the default browser to a different application and then back to firefox: System Settings > Default Applications > Web Browser This fix only removes the symptom. It is unclear why and how the default application setting has been corrupted and if other settings are affected in the same way.
Thank you for your bug report! However this bug report was created/provided previous to 01/01/2023 and also has not received any updates since before 01/01/2025. Unfortunately KDE neon no longer provides updates for anything older than noble 24.04 based edition's. Please upgrade to KDE neon noble and if you can reproduce the issue after upgrading to an active version, feel free to re-open this bug report. Thanks for understanding!