Possible reasons for a Class 'Elgg\ClassLoader' not found error?

I'm trying to help someone upgrade a 1.9 site to 1.10 (and further if this first upgrade would work). Current problem is that when trying to run upgrade.php there's the error


Fatal error: Class 'Elgg\ClassLoader' not found in /xxx/engine/lib/autoloader.php on line 39


I'm not sure what the reason for the error could be and how to fix the problem. Php 5.6 is installed (fastcgi handler used by Apache) and all required php extensions seem to be installed. Is there anything special necessary (in .htaccess) with fastcgi in use? Or what else could be the problem? I only give advice for the upgrade by email, so maybe the cause is something I haven't asked about yet.

p, li { white-space: pre-wrap;

  • As I remember upgrade from 1.9 to 1.10 has order: 1.9.0-1.9.8-1.10.0-1.10.6 (including update .htaccess).

    If using composer try to force a new dump of the autoload files:

    composer install && composer update && composer dump-autoload --optimize
  • Composer is not used.

    I think it should work to upgrade to latest 1.10 from any 1.9.x version. i suspect that some server config thing causes the problem but I can only react on the feedback of what fails and don't see it with my own eyes what's exactly going wrong.