If you are a recipient of a drawing (not the original author), you have three primary methods to resolve this error.
: Unlike standard dashed lines, complex linetypes embed specific shapes or text. AeccLand.shx provides the "definitions" for these embedded shapes (e.g., small tree symbols or specific dash patterns).
(.shx is also a compiled shape/font file used by AutoCAD):
Sometimes the file exists, but it is corrupted. Symptoms:
After digging around, here is what I found: