Site is Joomla 3.4.3 - updated from Joomla 2.x
Tried to install the weblinks extension (through the extension manager) over the currently installed extension resulting in the following messages: (other extension updates have been successful)
Warning
Error connecting to the server: SSL certificate problem: unable to get local issuer certificate
Error
Package download failed: https://github.com/joomla-extensions/weblinks/releases/download/3.4.1/pkg_weblinks_3.4.1.zip
If I were to uninstall the extensions first and upload the zip file to install, I'm not sure which to uninstall since there are several.
Please see #79 as this is a duplicate
You don't need to uninstall weblinks first. You can download the package to your computer and install it using the Install view of the Extension Manager; it will handle detecting an update just fine.