mozilla/pdf.js · error · Error

Invalid token in Form code

Error message

Invalid token in Form code

What it means

Thrown by Parser.parse() (top-level entry of the FormCalc parser) when the expression list was consumed but the lexer has not reached EOF. Any leftover, non-whitespace token after a complete declaration/expression list means the source is not a well-formed FormCalc program. Unlike the named Errors.* messages, this one is an inline literal string.

Source

Thrown at src/core/xfa/formcalc_parser.js:989

    return { special: "break" };
  }
}

class ContinueDecl extends Leaf {
  dump() {
    return { special: "continue" };
  }
}

class Parser {
  constructor(code) {
    this.lexer = new Lexer(code);
  }

  parse() {
    const [tok, decls] = this.parseExprList();
    if (tok.id !== TOKEN.eof) {
      throw new Error("Invalid token in Form code");
    }
    return decls;
  }

  parseExprList() {
    const expressions = [];
    let tok = null,
      expr;
    while (true) {
      [tok, expr] = this.parseExpr(tok);
      if (!expr) {
        return [tok, new ExprList(expressions)];
      }
      expressions.push(expr);
    }
  }

  parseExpr(tok) {

View on GitHub (pinned to 5903d58d58)

Solutions

1. Locate the byte offset of the unexpected token (the lexer tracks position) and remove or restructure the trailing tokens so the program ends cleanly at EOF.
2. Ensure each top-level declaration (var/func/if/for/while/foreach/block) is complete and that no statement spills past its terminator.
3. Re-serialize the XFA form script through a validated FormCalc authoring/export tool.
4. Isolate the script string and run it through a FormCalc lint/parse pass before binding it to the XFA template.

Example fix

// before (two top-level forms jammed together)
var a = 1 var b = 2
// after
var a = 1
var b = 2

// Cheap pre-check: the script should parse to exactly one expression list
// ending at EOF. Wrap the parser and treat any throw as 'do not bind'.
function isParseableFormCalc(src) {
  try { new FormCalcParser(src).parse(); return true; }
  catch { return false; }
}

try {
  const decls = new Parser(src).parse();
  bindDecls(xfaNode, decls);
} catch (e) {
  if (e instanceof Error && /Invalid token in Form code/.test(e.message)) {
    console.warn("FormCalc program has trailing/invalid tokens; skipping", e.message);
    return;
  }
  throw e;
}

When it happens

Trigger: A FormCalc script where valid declarations are followed by stray tokens (e.g. an orphan keyword, a second top-level construct the grammar does not allow, or trailing characters after 'endfunc'/'endif'). Reached when PDF.js parses an XFA form's 'script' or 'calc' content.

Common situations: Two statements concatenated without a legal separator; a trailing fragment left after deleting a declaration mid-edit; a generator that appends extra tokens; truncated or concatenated script content in a damaged XFA packet.

Understand the failure class

• Authentication and authorization failures — expired tokens, bad credentials, and missing scopes.

Related errors

• Invalid token in index.
• Invalid token in do ... end declaration.
• Invalid token in var declaration.
• Invalid token in func declaration.
• Invalid token if ... endif declaration.

AI-assisted analysis of mozilla/pdf.js@5903d58d58 (2026-08-13). Data as JSON: /api/errors/6fe18a259713592b. Report an issue: GitHub.