But can't find patch SUPEE-3941. Where can i find it? Thanks
You can get it from the community download page:
- release archive
- search for "SUPEE-3941"
- download the version for Magento CE 1.8
The patch fixes issues in the Magento Connect downloader, which is the same for Magento Enterprise and Magento Community.
It is here in the Magento download page under the Release Archive tab in the Magento Community Edition Patches - 1.x section (use CTRL/CMD + F to search 3941) :
You can also use this repo from Brent Peterson to get any patch: