If i unzip the roundcube 1.1.3 package I receive always the following error. Tested on 2 Computers with WinRAR 5.21
Works for me. Does the sha 256 checksum on the Roundcube download page https://roundcube.net/download/ match the .tar.gz file?
I don't know, where I can see that?
Here is a screenshot of the Archive-Settings
(http://www2.pic-upload.de/img/28789262/Unbenannt2.png)
I only know how to do it on a unix command line, not sure how in Windows. Maybe try Google?