A Lua script stopped with an error

What ArduPilot says:

• Error: …
• Unable to load the file: …
• Unknown error (N) loading …
• Engine Error: …
• Lua: …
• … did not return a delay (0xN)

Script errors reach you as “Lua: …”, usually with the file name and the line number. “Error: …” means the file could not even be read as Lua (a syntax error); other texts are errors met while running. “did not return a function”, “did not return a delay” and “returned bad result count” mean the script's update function did not end the way ArduPilot expects: with the function to call next and the delay in milliseconds. The failed script is removed and not run again; the others carry on. The line is repeated every 10 seconds, ten times.

What to do, most likely first

1. The script was written for another firmware version, and a function it calls has changed or is missing.

   CheckThe text says “attempt to call a nil value” or “bad argument”, with a line number.

   FixTake the script from the same version as your firmware; the Lua Applet Catalog lists every applet per version.

2. The script needs something that is not there: a module file, its own parameters, a device.

   Check“module … not found” means a file is missing from APM/scripts/modules. Read the applet's own instructions for the parameters it expects.

   FixCopy the modules next to the script, set the parameters it asks for, and reboot.

3. A mistake in your own script.

   CheckGo to the line number in the message.

   FixCorrect it and reboot or restart scripting. An update function must end with a line like “return update, 100”.

“Panic: …” (4.6) and “Engine Error: …” (4.7) are errors in the engine itself, outside any one script. 4.6 throws all scripts away and loads them again from the start; 4.7 ends the engine, and “Scripting: stopped” follows.

Parameters to look at

Where to do it:Lua Applet Catalog