There are several cause due to which we are unable to install any extensions some are given below. some of the common issues are "Warning! failed to move file" and "JFolder::create: Could not create directory" So following are the list of the steps by which we can avoid such type of issues while installing any extension.

1 tmp directory

In Joomla when any extension uploads it moves to tmp directory and if its not writable it will gives you error in order to avoid this always provide permission to tmp folder.

2 Directory permission issue

Directory permission is required when we are uploading any extension in joomla as joomla moves upload file from tmp directory to specific folder for eg if extension is component then it moves from tmp to component folder and if component directory is not writable it will not work and provides you error.

3 Zip library not installed

All the extensions in Joomla are zipped format for installation purpose and if zip library not installed in php then Joomla will be unable to install extension and provides you error. As Joomla reads zip format extension and needs to unzip it in appropriate folder.