Here's more details on my issue. The issue involves my older Windows 7 computer where I have my older programs are installed (2011-2018) and used on an infrequent basis as needed. I know Windows 7 is no longer supported by Microsoft so I only use it online to obtain updates for these programs when needed. 

I opened each program and did the update but noticed that a component of the update was blocked by the Windows Firewall. I was no longer able to open 2016, 2017 and 2018 after the update. I then turned off the Windows Firewall and without opening the software attempted another update again using the program file folders for each year. For each of those years I get the message that no further updates are available. For 2018 you can refresh the updates also using the program file folder, but not for 2017 and 2016. In either event doing the refresh for 2018 did not fix the problem.

Here's the message I get when trying to open 2016, 2017 and 2018.........

Sign in Completion failed. Could not load file or assembly 'System.Net.Http, Version=4.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file spedified.  

Can anyone in the Community or Tech Support help me resolve this issue?

Thank you!