apple/pkl · error · GenericParserError

invalidLineContinuationEscapeSequence

invalidLineContinuationEscapeSequence

Error message

Invalid line continuation escape sequence.

What it means

A `\` line-continuation escape was found inside a string literal in an invalid position (e.g. not at end-of-line), so the parser rejects it. Pkl only allows the continuation escape immediately before a line break.

Source

Thrown at pkl-parser/src/main/java/org/pkl/parser/GenericParserImpl.java:982

    var start = next();
    children.add(makeTerminal(start)); // string start
    while (lookahead != Token.STRING_END) {
      switch (lookahead) {
        case STRING_PART -> {
          var tk = next();
          if (!tk.text(lexer).isEmpty()) {
            children.add(make(NodeType.STRING_CHARS, tk.span));
          }
        }
        case STRING_ESCAPE_NEWLINE,
            STRING_ESCAPE_TAB,
            STRING_ESCAPE_QUOTE,
            STRING_ESCAPE_BACKSLASH,
            STRING_ESCAPE_RETURN,
            STRING_ESCAPE_UNICODE ->
            children.add(make(NodeType.STRING_ESCAPE, next().span));
        case STRING_ESCAPE_CONTINUATION ->
            throw parserError("invalidLineContinuationEscapeSequence");
        case INTERPOLATION_START -> {
          children.add(makeTerminal(next()));
          ff(children);
          children.add(parseExpr(")"));
          ff(children);
          expect(Token.RPAREN, children, "unexpectedToken", ")");
        }
        case EOF -> {
          var delimiter = new StringBuilder(start.text(lexer)).reverse().toString();
          throw parserError("missingDelimiter", delimiter);
        }
      }
    }
    children.add(makeTerminal(next())); // string end
    return new Node(NodeType.SINGLE_LINE_STRING_LITERAL_EXPR, children);
  }

  private Node parseMultiLineStringLiteralExpr() {

View on GitHub (pinned to f3efcbfc9b)

Solutions

1. Remove the stray `\` if no escape was intended
2. Place the `\` immediately before the newline to continue the string, with no trailing spaces
3. Escape backslashes properly: write `"C:\\temp"` for a literal backslash

Example fix

// before
val p = "C:\temp"
// after
val p = "C:\\temp"
// or a real continuation:
val s = "first \
second"

/\\[^\n]/.test(src) // a backslash followed by something other than newline inside string content — likely an invalid continuation or needs doubling

When it happens

Trigger: The lexer produced a STRING_ESCAPE_CONTINUATION token where it is not a valid line continuation — e.g. `\` followed by characters on the same line inside a string.

Common situations: Escaping a trailing backslash unintentionally (Windows paths like "C:\temp" pasted into Pkl strings); a regex or path written without doubling backslashes; stray `\` before a non-newline character.

Related errors

• invalidUnicodeEscapeSequence
• missingDelimiter
• unexpectedEndOfFile
• stringContentMustBeginOnNewLine
• notAUnion

AI-assisted analysis of apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/46dcd0f0b746d767. Report an issue: GitHub.