error/qtype combined/nosubquestiontypesinstalled
From MoodleDocs
In order for the Combined question type to work, You need to have installed in your Moodle server one or more of the following four additional question types:
- Numeric (n.b. based on Variable numeric and not Numerical)
- Pattern match
- OU multiple response
- Select missing word
PPlease install one or more of this additional plugins from the Moodle plugins database and try again.
