Simply closing the ESO Launcher completely and relaunching may resolve your issue with being unable to decompress the patch data. If it doesn't, you should check to ensure you have the correct exceptions in your anti-virus software.
The application files that may require exceptions are:
Some antivirus programs require entire folders to be selected instead of a single file.When this is the case, the file paths below are what players should use. If required by the anti-virus program, include all subfolders since every file is critical to run the game.