Based on your error has found, you can try some step like this below: 1. You must make sure that all of module has installed on your moodle is 1.9 version or later. 2. Please try to change your theme with other theme in Theme Selector 3. Install again your Certificate Module. Step to reinstall are: Delete fitur Certificate from Activities Module; Delete Sertificate Folder in /mod directory. End then install again sertificate module like step has send before. Thus of my advise. I hope can solve your problem. Thank you.