Form gives validation error everytime unless page is refreshed

I have a php/html/form that is giving me problems. What happens is the form gives me validation error upon submitting unless I refresh the page and get it correct the first time. If I input incorrect validation then I must refresh the page again or else it will give me error over and over. And it must be correct the very first time after page load, or else it will just keep giving error until you refresh and get it . the. very. first. time. lol

After that I am would like to pass the user submitted data to the next page using php.

<form action='load' method='GET' onsubmit="return Validate();">
      <div>
        <input type="text" placeholder="Enter btc address" name="btcaddress" pattern="^[13][a-km-zA-HJ-NP-Z1-9]{25,34}$" oninvalid="setCustomValidity('Correct address format required.')" required>
      </div>
      <center>
        <button type="submit"><b>Go</b></button>
      </center>
    </form>

Could this be happening because I am testing on my linux machine with Atom and the PHP Server plugin? Address http://localhost:8000