Hello.
I can suggest that your server does not have enough memory or time for the script execution (activation).
You can increase these values at the php.ini file at your server configuration.
If its not help, please try to deactivate all other active plugins, then activate Booking Calendar and, if success, then activate one by one other your active plugins.
Otherwise, please find the error.log at your server and recheck it about the reason of that issue. If you can not find it, please contact the support of your hosting company to find it.
Kind Regards.
Do you know the value setting to increase the PHP script execution time?
I have increased the memory limit to 128M.
Thanks
Set script execution value to 120 seconds.
Then retest.
If not help, please check one by one all my other suggestions from previous reply.
Kind Regards.
That fixed it, thanks a lot! 🙂