Image Transform Internal Server Error (500 code) after Craft CMS update I just updated an "older" Craft site (version 2.4.2702) to the newest update (version 2.6.2958).

But now all my image thumbnails in the back-end are missing and if I upload any new assets, the thumbnail is not generated and I get a Internal Server Error 500 on the front-end as the URL it points to is still the cpresources/transforms/283?x=qFc4lFWR5 kind of URL.

The image thumbnail itself is also not generated anymore in the folder it is supposed to go in. I didn't change any folder permissions (only updated the new app folder ofcourse with the correct permissions). I'm able to upload assets so the permissions should be fine I guess.

I've had issues like this before, but those were resolved, so I don't know what is causing this issue again. Is there anything I forgot about this update that I needed to change? I needed to do a manual update.

The logs I get are these:

2017-01-17 10:13:26

Level   info
Category    application
Message [Forced] Finished task 14 (GeneratePendingTransforms).
2017-01-17 10:13:26

Level   info
Category    application
Message [Forced] Starting task GeneratePendingTransforms that has a total of 0 steps.


UPDATE

I do get a PhP error:

[18-Jan-2017 14:04:07 UTC] PHP Fatal error: Call to undefined method Imagine\Imagick\Imagick::getImageAlphaChannel() in MY-BASE-PATH-HERE/craft/app/vendor/pixelandtonic/imagine/lib/Imagine/Imagick/Imagick.php on line 191


But through the PhPInfo in the Craft CP I can see that Imagick extension 2.2.2 is installed with ImageMagick 6.7.2-7, so according to this page the method should exist: http://php.net/manual/en/imagick.getimagealphachannel.php.

UPDATE 2

As I dumbly clicked "rebuild all asset indexes" on the live site (instead of on the local development site in the browser tab next to it aaargh) I quickly added 'imageDriver' =&gt; 'gd', to the config as a workaround.
More a workaround than a solution but I added 


  'imageDriver' => 'gd'


 to the config so it didn't use Imagick anymore. Works as supposed to now.