Installing and upgrading help

PHP 7.3 isn't released yet (it's only a release candidate, full release is due in December). So you are best off downgrading for the time being!

7.2 is fine but, as has been pointed out, there isn't a stable 7.3 yet.

php eol

http://php.net/supported-versions.php

Branch     Initial Release     Active Support Until     Security Support Until
7.0     3 Dec 2015     2 years, 11 months ago     3 Dec 2017     11 months ago     3 Dec 2018     in 13 days

So no 7.0 php would be worth your time.

And 2 cents more ...

Registration with moodle.net does not include PHP version.

Site admins are expected to know.  Wonder how many are relying on provider
(where hosted) to assure all hosted customers are using a supported for security at
least version of PHP?

Story ... allow please ...

Not long back ago, SiteGround had a real battle with customers that hosted Joomla's
with them.  SG had one of those easy install things but no way to update Joomla sites.
Many, many, many vulnerable 1.5.x Joomla sites on SG.  Even though SG may have
contacted customers, customers hadn't a clue as to how to upgrade.   To make matters
worse, Joomla itself had no 'easy' path to from 1.5.x to 2.5 - plus released a version 3 to boot ... no hyperjump possible.

Result: customer's didn't upgrade.  SG finally had to get tough ... told customers if they did not upgrade from their 1.5.x their sites would be disabled.

Hmmmm ... Moodle doesn't have either update nor upgrade built in.

Now if I were a blackhat and had an exploit that I had tested vs php 7.0 and it was known to work on 7.0.x sites, I'd wait til the day after the EOL date (14 days from now) to have maximum
impact on sites attacked ... owned, etc..

Moodle:

Moodle 3.5.x

https://docs.moodle.org/dev/Moodle_3.5_release_notes

    PHP version: minimum PHP 7.0.0 Note: minimum PHP version has increased since Moodle 3.3. PHP 7.1.x and 7.2.x are supported too. PHP 7.x could have some engine limitations.

Wouldn't it be nice to get a heads up from Moodle concerning version of PHP?  Should environment check now be updated to inform Moodle admins?

My 2 cents ...

'spirit of sharing', Ken

Thank you for your kind and great answers (Dan, Howard, and Ken).

Unfortunately, Linode my hosting provider in its Centos7 VPS has installed: PHP 7.3.0RC5 (cli) (built: Nov  6 2018 10:22:47). Which means that if I don't downgrade to PHP72 I will not be able to upgrade via git pull my Moodle.

At PHP timetable the release for PHP 7.3 General Availability (GA) is December 6th, I guess Moodle will be able to work with no problem with PHP73 after that date.

Manuel.

PHP 7.0 can be used with Moodle 3.0.1, Moodle 3.1 and later releases. It is also the minimum supported version for Moodle 3.4
PHP 7.1 can be used with Moodle 3.2 and later releases
PHP 7.2 can be used with Moodle 3.4 and later releases