I didn't know this site exists. So, I asked it on [WebApps](https://webapps.stackexchange.com/questions/5539/how-to-prevent-plugin-theme-installation-failures-on-wordpress)

I didn't get a solution still. :-(

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I am unable to install any theme/plugin to my WordPress 3.0

```
Downloading install package from http://downloads.wordpress.org/plugin/contact-form-7.2.3.1.zip…    
Unpacking the package…    
Installing the plugin…    
Could not copy file. /public_html/blog/wp-content/plugins/contact-form-7/languages/wpcf7-lt_LT.po    
Plugin install failed.

Downloading install package from http://wordpress.org/extend/themes/download/piano-black.2.2.zip…
Unpacking the package…
Could not create directory. /public_html

Downloading install package from http://downloads.wordpress.org/plugin/contact-form-7.2.3.1.zip…
Unpacking the package…
Could not create directory. /public_html/blog/wp-content/upgrade/contact-form-7.tmp/contact-form-7

```

I get similar messages everytime. Is there any solution?