[half-opened]

I ran blockMesh and got the error message below:

--> FOAM FATAL IO ERROR: 
Attempt to return dictionary entry as a primitive

file: /home/dnrmehd/OpenFOAM/dnrmehd-11/run/test1/system/blockMeshDict/boundary from line 53 to line 76.

    From function virtual Foam::ITstream& Foam::dictionaryEntry::stream() const
    in file db/dictionary/dictionaryEntry/dictionaryEntry.C at line 83.

and blockMesh file is

/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  11
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      blockMeshDict;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.01;

vertices
(
    (0 0 0)      // 0
    (10 0 0)     // 1
    (10 10 0)    // 2
    (0 10 0)     // 3
    (0 0 12)     // 4
    (10 0 12)    // 5
    (10 10 12)   // 6
    (0 10 12)    // 7
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (20 20 24) simpleGrading (1 1 1)
);

edges
(
    arc 0 1 (5 5 0)
    arc 1 2 (10 5 5)
    arc 2 3 (5 15 0)
    arc 3 0 (-5 5 0)
    arc 4 5 (5 5 12)
    arc 5 6 (15 5 12)
    arc 6 7 (5 15 12)
    arc 7 4 (-5 5 12)
);

boundary
{
    walls
    {
        type wall;
        faces
        (
            (0 3 7 4)
            (1 2 6 5)
            (0 1 5 4)
            (2 3 7 6)
        );
    }
    bottom
    {
        type wall;
        faces
        (
            (0 3 2 1)
        );
    }
    top
    {
        type wall;
        faces
        (
            (4 5 6 7)
        );
    }
}

mergePatchPairs
(
);

// ************************************************************************* //

what should i do