The configuration file could not be opened. #15409

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Describe the issue The configuration file could not be opened. when clicking on Open Configuration File

What behavior did you expect? Expected to open bitcoin.conf

<!--- What was the actual behavior (provide screenshots if the issue is GUI-related)? -->

How reliably can you reproduce the issue, what are the steps to do so? Lanuch Bitcoin Core

What version of Bitcoin Core are you using, where did you get it (website, self-compiled, etc)? https://bitcoin.org/en/download v0.17.1

What type of machine are you observing the error on (OS/CPU and disk type)? OSX

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<!--- This is normally the contents of a `debug.log` or `config.log` file. Raw text or a link to a pastebin type site are preferred. -->

The configuration file does not exist by default. However, it could be created when selecting that button.

Related: #12722

To clarify. When I click Open Configuration File it creates the bitcoin.conf file but it does not open it. Instead it shows The configuration file could not be opened.

I'm able to edit the conf file manually, but I expected that file to open in some text editor.

I find that the QT wallet fail to open the configuration file on Mac, when these is no default application for *.conf files.

Here is a feasible way to solve this bug. When QDesktopServices::openUrl fails to open file:///path/bitcoin.conf with its default application, use QProcess::startDetached to run open -t /path/bitcoin.conf command instead, so as to open the configuration file with system's default text editor.

For more details, see this PR #16044.

@shannon1916 BTW... Same thing happens on Windows 10 which doesn't provide a default association with .conf files. Double clicking any .conf file and assigning a default app to it fixes the problem in windows as well.