Additional info:
php 7.3

[16-Apr-2019 05:23:55 UTC] PHP Warning:  Use of undefined constant PIWIK_INCLUDE_PATH - assumed 'PIWIK_INCLUDE_PATH' (this will throw an Error in a future version of PHP) in /home/site/public_html/matomo/core/bootstrap.php on line 30
[16-Apr-2019 05:23:55 UTC] PHP Warning:  require_once(PIWIK_INCLUDE_PATH/core/testMinimumPhpVersion.php): failed to open stream: No such file or directory in /home/site/public_html/matomo/core/bootstrap.php on line 30
[16-Apr-2019 05:23:55 UTC] PHP Fatal error:  require_once(): Failed opening required 'PIWIK_INCLUDE_PATH/core/testMinimumPhpVersion.php' (include_path='.:/opt/cpanel/ea-php73/root/usr/share/pear') in /home/site/public_html/matomo/core/bootstrap.php on line 30

Can you post the first ~20 lines from piwik.php and index.php?

Hi there,

it sounds like some file wasn't copied properly during the update. I recommend you update the files again using the manual update see https://matomo.org/docs/update/#the-manual-three-step-update

Make sure to backup your config/config.ini.php and do not delete it as mentioned in the docs. This should fix your issue. Let us know if this doesn't work and we're happy to look at it again and reopen the issue.

FYI this turned out to be a php include_path config issue.

FYI this turned out to be a php include_path config issue.

Would you mind letting me know how you've solved this? Looks like I'm facing the same / similar issue... Thanks!

I read, that set_include_path() may fail if you setup an include path in your php.ini. So, you could check if that is the case for you and if yes, comment it out and test it again?

I don't recall everything, but here's what I do recall:

1. I use WHM and in efforts to secure things, I had configured php open_basedir to be limited to user home and in my configuration, I had to add another value to set include_path to start there as well as setting upload_tmp_dir. Those changes were done in system_pool_defaults.yaml
2. Eventually I enabled ini_set after numerous other security things were done first.
3. I initially modified the matomo/core/testMinimumVersion.php commenting the exit(1) at the end before doing adding support for windows phone 7 version 7.5 #1 and Using alternate database. #2 above.