Getting this error when trying to upgrade WordPress?
Download failed.: SSL certificate problem: unable to get local issuer certificate
1. Download the cert.pem file from here. Right click on the link and click save link as.
2. Place the cert.pem file in your php folder.
IE: C:\Program Files (x86)\PHP\v5.5\cacert.pem
3. Edit the php.ini and search for “curl”. Edit the curl.cainfo line with the following.
curl.cainfo = “C:\Program Files (x86)\PHP\v5.5\cacert.pem”
Save the php.ini file.
4. Now try your upgrade again. I didn’t have any issues after performing those steps.