“Call-time pass-by-reference” has been depreciated in PHP for some time, and only generated butt-loads of PHP warnings (invisible to users). But on PHP v5.4 and above, it throws fatal errors, and prevents any WP page, including wp-admin pages, from loading.
I just discovered the hard-way that Instapress v1.5.3 is using “Call-time pass-by-reference” and will bring down WP sites on PHP v5.4 and above.
There is a simple fix for plugin developers referenced here:
I look forward to using this plugin once again, if/when it is updated.