Great, if an error message one can stay as long, although the solution is so simple.
Class 'Imagick' not found in ...
Thus, only one was missing in the Windows system environment variable, which must be set as follows.
Computer-> right click-> Properties-> Advanced-> Environment Variables-> User ..
MAGICK_HOME = path / to / Imagick / config files (eg C: / Imagick / config)
Many thanks to Mikko's blog for the answer!
