Error reference / classDiagram
A relationship arrow is missing a dash, so Mermaid can't recognize it as one of the defined class relationship types.
Parse error on line 2:
...ssDiagram A -|> B
----------------------^
Expecting 'LINE', 'DOTTED_LINE', got 'ALPHA'classDiagram relationship arrows are two characters plus a symbol: --|> for inheritance, --* for composition, --o for aggregation, ..> for dependency. A single dash before the symbol (-|> instead of --|>) isn't a recognized arrow, so the parser fails right after it.
Use the full two-character line: --|> for inheritance/realization, --* for composition, --o for aggregation, --> for association, ..> for dependency, ..|> for interface realization.
Fails to parse
classDiagram
A -|> BRenders correctly
classDiagram
A --|> BA node ID exactly matches a Mermaid keyword (call, click, or href) and is referenced without a shape, so the parser reads it as a click-callback token instead of a node name.
A node's square-bracket label was never closed, so the parser runs into the next node's opening bracket before it finds the one it was expecting.
A square-bracket label contains a raw ( or ), which Mermaid reads as the start of a different node shape rather than as label text.