Starting a new year and as usual, I’m upgrading my lab and studying to upgrade my certifications as well.
I took the decision to start working on my vCenter to upgrade it the latest version (vCenter 7). As I’m a macOS user, I came across into a problem when trying to open Installer app:
“Installer can’t be opened because Apple cannot check it for malicious software”
Here’s the Problem
Once I downloaded VMware VCSA from https://www.vmware.com/, I opened ISO file:

Went to Installer app:

And the Gatekeeper windows just appear along with the error I stated in:

I tried a Work Around (no lucky…)
Click on Show in Finder:

Select Installer again:

Click in Open:

And now I have the open to Open the Installer without problem:

vCenter Server Installer opened in a good way!

Well… as I tried to work around using this method, if a new software is requested (e.g: Libcurl), I ended up with the same problem before. So, this definitely is not a good solution for this problem.

… Now To Solve It
Apple states this is a designed security to ensure that only trusted software runs on macOS. You can find more information about it on this link: https://support.apple.com/en-us/HT202491
To make it work and moving forward to upgrade my lab, I opened Terminal and typed the following command:
sudo spctl --master-disable

After you type your password, this command makes Security & Privacy app to select Anywhere option, which solves this problem:

Now you can move forward with your upgrade and vCenter installation.
Enjoy the ride!