Before files upload, ENABLE MAGENTO CACHE : this will prevent Magento to try to install extension before all files are uploaded.
Also, if you have any :
- APC cache
- Redis cache
- Activated the Compilation of Magento
-> Please disable them
Open the file “app/etc/local.xml” and check for / switch off any other extra caches.
You just need to upload this file structure to your server on the same file structure provided by Magento.
No code file will be erase : All the code files will be available into /app/code/community/MDN
Once all files are copied, please follow here under steps to make sure it is well installed:
Refresh cache (System menu > Cache settings): If you get any error message at this stage, it means that there are some problems with the installation.
Refresh indexes (System > Index management)
Disconnect and reconnect yourself from Magento’s back office.
Unzip the archive and upload it into your remote web site.
Once all files are uploaded, you have to refresh both magento and index caches.
Once caches are refreshed, log out and login from admin panel (to reset permissions).