I'm not sure that what you describe is what I've experienced.

We were (are still) running MW 1.21.1 with PHP 5.3.29. Our host upgraded to PHP 5.5 as default, and will soon discontinue support for PHP5.3.

MW 1.21 was advertised as "requires PHP5.3 or higher". I took that to mean PHP5.5 would not cause any problems.

As soon as the switchover happened, we had a screen full of error messages rather than wiki pages. I set the .htaccess to use PHP 5.3, and we now have a functioning wiki again.

However, I have no idea how long it will be before our host dumps PHP 5.3 entirely, so we now have an upgrade forced on us, like it or not. This would not be a such a bad thing if the upgrade process were a little less fraught with uncertainty and room for errors, but it can sometimes be a bit nerve wracking.

I see that you mention LTS, and that 1.21 apparently slipped between the LTS versions. Too bad for us. My recollection is that we upgraded from 1.19 to 1.21 for the same reason - PHP updated and the version we had no longer worked.

And it looks like we are (somewhat counter-intuitively) better off upgrading not to the current 1.26, but to 1.23, which is an LTS version.

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Message: 1 Date: Mon, 7 Dec 2015 17:27:14 -0700 From: Bryan Davis bd808@wikimedia.org To: MediaWiki announcements and site admin list mediawiki-l@lists.wikimedia.org Subject: Re: [MediaWiki-l] MediaWiki-l Digest, Vol 147, Issue 9 Message-ID: CAGrKmBLWn7t0jwrRhudkdTZQpXZjFo7MquMm1zbEQBhbQAOmSw@mail.gmail.com Content-Type: text/plain; charset=UTF-8

On Mon, Dec 7, 2015 at 3:39 PM, Mickey Feldman mfeldman@vigil.com wrote:

...

One more vote for this.

Upgrades have generally caused us much pain with little or no obvious benefit. In our particular case, Mediawiki works well enough as is. Until our host decides to update PHP forcing us to upgrade Mediawiki, and discovering that it no longer works.

While there may be things we might like improved, we can't afford to dedicate a full time Wikimedia guru to becoming expert in the hidden corners of the code and keeping up with every change that might have some unexpected side effect.

I realize that some of the changes are security fixes, and a Good Thing, but I suspect these are in the minority. Our wiki is not public, so we could probably get away with being a bit more lax about that, but when Mediawiki is suddenly no longer compatible with php version-whatever, we have no choice but to upgrade.

I've seen a couple of comments similar to this one that seem to have the causal chain reversed so I thought I would try to clarify.

If and when MediaWiki updates its minimum required PHP version nothing will change for existing MediaWiki deployments. The change will only effect new MediaWiki releases. If you are happily running MediaWiki 1.23 or similar on your wiki nothing at all will change.

If and when your hosting provider updates their installed PHP version nothing will change for existing MediaWiki deployments. PHP generally goes out if its way to maintain backwards compatibility with running software designed for older versions of the PHP runtime. In the few cases that there are backwards compatibility breaking changes it is very likely that MediaWiki has already been patched to deal with them unless you are running a version of MediaWiki that predates the initial release of the new PHP version your provider has upgraded to. In that case if you are running a supported LTS version of MediaWiki you should only need to upgrade to the latest point version. If you are running something older than a supported LTS release, yes you may have to upgrade.

Bryan