I have developed a private plugin, that is distributed and installed as a zip file. With this plugin users can upload files and the files will be stored inside the plugin’s directory.
Now, I’ve got the problem, that I can not upgrade this plugin. If I try to upload a newer version, the installation will fail, because the directory already exists.
Some people suggested to uninstall the old version first, but this is impossible for me, because then all uploaded files will be lost.
Have you any suggestions to solve my problem?