SUMMARY

The desktop file:

[Desktop Entry]
Exec=ls 
Name=Terminal test
Terminal=true
TerminalOptions=--hold
Type=Application

should launch the default terminal application and execute the command.  However, as reported on bug #421364, if the desktop file is launched with 'kioclient5 exec test.desktop' or by any other means an error box is shown:

  Unknown error code 100
  Could not find the program 'konsole'
  Please send a full bug report at https://bugs.kde.org.

with the debug message:

  kioclient(1227906) findNonExecutableProgram: Internal program error.
  QStandardPaths::findExecutable couldn't find "konsole" but our own logic found it
  at "/usr/bin/konsole" . Please report a bug at https://bugs.kde.org

The problem seems to be in KIO::DesktopExecParser::resultingArguments() where, if service.terminal() is true, the user's configured terminal application or konsole as a default is prepended to the command line (with appropriate options).  However, this is most likely to be a relative path.  This then triggers the "nonExecutable" check in KProcessRunner::KProcessRunner().

STEPS TO REPRODUCE
1.  Execute the desktop file as above using kioclient5.

OBSERVED RESULT

Error and debug messages as above are shown, and no terminal is launched

EXPECTED RESULT

A terminal is launched and the current directory is listed

SOFTWARE/OS VERSIONS
KDE Frameworks Version: 5.71.0
Qt Version: 5.14.2