Joomla 1.5.20 - "Warning! - Failed to move file"

When you try to install any extension like  modules, components, plugins, languages or templates in Joomla in version 1.5.x an error could occur that says: "Warning! - Failed to move file".

That is because Joomla doesn't have the writing rights after a fresh install for the affected folders.
Following folders should be write enabled for any extension you upload:

joomla_base/tmp
joomla_base/language
(sometimes: joomla_base/logs)

Then depending on if you upload a administrator(backend) or a user(frontend) extension the according folder needs to be write enabled. That could be:

joomla_base/modules
joomla_base/components
joomla_base/plugins
joomla_base/templates
or

joomla_base/administrator/modules

joomla_base/administrator/components

joomla_base/administrator/language

joomla_base/administrator/templates

In Unix/Linux systems the CLI command would be:

chmod -R 777 language

Where -R stands for recursive all subfolders and files of the folder "language".

Warning: Failed to move file! in Joomla Media Manager

When you try to upload a file in Joomla 1.5 via the Media Manager of the Backend you could run into a similar error as described above.

Warning: Failed to move file!
Error. Unable to upload file.

To solve this problem you need to write enable the images folder in the joomla base path. Not the media folder!
chmod -R 777 images