Fatal error: Call to undefined function is_plugin_active() in /home/content/26/11868026/html/wp-content/plugins/jetpack-lite/jetpack-lite.php on line 12
is_plugin_active() function is present in WordPress since 2.5 as you all can see in the codex and min WP version requirement for the plugin is set to WP 3.1.
So... Which WordPress version are you using? Because the error you posted indicates that is_plugin_active() function is not present in your WordPress, and that only can happen if you're running a very outdated WordPress version and not matching the requirement of the plugin.
I have Jetpack Lite running without any problem in dozens of sites running WordPress 3.8.
Assuming Jetpack Lite gets updated to fix this problem, is the new design philosophy going to be as lightweight as before? I'll end up with two plugins instead of one. Is resource usage going to be heavier now that Jetpack Lite is suppressing most of Jetpack's features instead of being slimmed down version of Jetpack?
When I created Jetpack Lite years ago, I did it as fork of Jetpack because no other method to do was available at that moment.
Fortunately, today Jetpack can be trimmed down without the need of making a fork. That's why I changed the way Jetpack Lite do the work. In fact, now, Jetpack Lite doesn't use any resource, it only says to Jetpack to only load the Stats and Shorlinks modules, so the other modules won't load or consume any resource.
This way is much better, because now you don't need to wait for me to update a whole new plugin when a new Jetpack gets published. So you'll get updates to the modules you want to use faster than before.
You might have added an update notice to make people aware and not just kill sites if they don't have Jetpack installed. With more than 40K downloads it is your duty to inform your users when you make such dramatic changes to your plugin!
The changes are informed in the upgrade notice and in the changelog. Your WordPress installation is your responsability not mine, so it's your responsability to check changes before installing anything, to check requirements, or to have a way to rollback if something fails.
And, by the way, more than 200 people downloaded the plugin in the latest 24h and only 8 people are complaining (1 of them without even installing the plugin) here...
What about to stop a moment and think that maybe the problem can be in your side?? what about to read first and blame later? What about to have a little of respect for someone that brings his work and time to you without asking anything in return?