JSON error When create new invoice

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1 
dashboard#:1 Uncaught SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at Object.eval [as success] (eval at <anonymous> (jquery-1.12.3.min.js:2), <anonymous>:28:61)
    at i (jquery-1.12.3.min.js:2)
    at Object.fireWith [as resolveWith] (jquery-1.12.3.min.js:2)
    at y (jquery-1.12.3.min.js:4)
    at XMLHttpRequest.c (jquery-1.12.3.min.js:4)

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