5
There are two possibilities. The first, as Mamba said, not all files have been uploaded to the server.
The second possibility is the lack of pre-arranged access rights (chmod 777) to a directories. Make sure that you did the installation instructions:
Make the directory: xoops_data / writable;
Create (if not Already present) and make the directories:
xoops_data / caches /
xoops_data / caches / xoops_cache /
xoops_data / caches / smarty_cache /
xoops_data / caches / smarty_compile /
writable.