E805 - Template render failed

Cause

Rendering a template raised an error other than a syntax error (E801) or an undefined variable (E802) — e.g. an unsupported operation on a param value whose structure doesn't match what the template expects (passing a string where the template iterates a list).

Example

{ template_file: "grid.elements.json.j2", with: { thumbs: "not-a-list" } }

How to fix

Compare the value passed in with: against how the template body uses it; param type: declarations in front-matter catch top-level mismatches earlier (E804), but structure inside array / object params is the caller's responsibility.