Looks like you are using HTTPS Connection, that means you need to have wallet, - SSL Certificate configured properly on database. Second, you need to create / assign ACL Privileges as Oracle can't and won't allow unauthorized SSL access.
Check this link for info https://oracle-base.com/articles/misc/utl_http-and-ssl
i advise to move the logic on database procedure / function and call that function from your button press trigger and pass parameters.
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