SSMS 18.4 installation will not run - ssms

Question

I am having trouble installing SSMS on a fresh installation of Windows 10 - on a new Dell XPS 15.
I am installing the latest version (18.4) from here: https://learn.microsoft.com/en-gb/sql/ssms/download-sql-server-management-studio-ssms
When I run SSMS-Setup-ENU.exe I get the User Access Control dialogue, I say Yes and nothing happens.
I cannot see any processes starting in Task Manager.
Logs indicate that the installationg cannot start. From googling this error suggests that I'm missing a version of dotnet framework.
I have installed Visual Studio 2019 + all the dotnet frameworks (everything from 4.6 to 4.8) + Dotnet Core.
Does anybody have any ideas - what am I missing or doing wrong? :/
Thanks for your help!
Error (ommitting all of the noise)
[2E90:33E8][2019-12-09T10:55:43]i000: Loading managed bootstrapper application.
[2E90:33E8][2019-12-09T10:55:43]e000: Error 0x80131902: Failed to create the managed bootstrapper application.
[2E90:33E8][2019-12-09T10:55:43]e000: Error 0x80131902: Failed to create UX.
[2E90:33E8][2019-12-09T10:55:43]e000: Error 0x80131902: Failed to load UX.
[2E90:33E8][2019-12-09T10:55:43]e000: Error 0x80131902: Failed while running
[2E90:33E8][2019-12-09T10:55:43]e000: Error 0x80131902: Failed to run per-user mode.
[2E90:33E8][2019-12-09T10:55:43]i007: Exit code: 0x80131902, restarting: No
Installed dotnet framework
PS C:\> wmic /namespace:\\root\cimv2 path win32_product where "name like '%%.NET%%'" get version
Version
4.5.50932
4.8.03928
4.6.01055
4.7.02558
4.5.50710
24.64.28315
3.0.1.0
4.8.03761
3.0.1.014347
13.0.19213.0
4.7.03081
4.7.02053
12.16.14727
24.0.28113
4.7.02558
3.1.0.0
4.7.03062
12.2.18292.0
3.1.0.014727
12.0.30731
24.64.28315
2.1.14.014727
1.0.20910.0
4.6.01590
4.7.02053
24.4.28216
4.8.03928
2.1.14.0
24.64.28315
4.8.03761
4.8.03928
3.0.0127.060
3.1.0.0
16.120.28209
4.6.00081
24.64.28315
3.1.100.014727
3.0.1.0
24.64.28315
24.4.28216
4.0.30319
3.1.0.0
4.5.51651
4.7.02558
4.6.01055
4.7.02558
4.6.01590
24.64.28315
24.64.28315
24.64.28315
3.0.1.0
24.0.28113
24.4.28216
16.4.457.38025
4.6.01590
4.7.03062
24.64.28315
3.0.1.014727
24.4.28216
4.7.02053
24.4.28216
4.6.01055
24.64.28315
4.8.03761

Answer 1

Argh I have worked out my problem - it's pretty dumb.
I forgot that I updated the machine.config with some settings but there was a mistake and missing a closing ". This meant that the configuration was invalid and therefore the installer wouldn't run. 🙈🙈

Answer 2

WE had similar problem:
Issue 1:
The management studio update checker package did not load correctly.
The problem may have been caused by a configuration change or by the installation of another extension.
Restarting Visual Studio could help resolve this issue.
Issue 2:
The configuration section 'system.web' cannot be read because it is a missing a section declaration.
\?D:\wwwroot\testsite\web.config
While troubleshooting, we found that .NET Framework directory for 32 bit 4.7.1 was missing required config directory which contains necessary default machine.config file. These files are necessary for all applications to run. We copied the files from a working server on to the server which had the problem. We were then able to use current SSMS (v18.4) as well as upgrade it to v18.6. Also, IIS level config errors were gone.
Directory path: C:\Windows\Microsoft.NET\Framework\v4.0.30319\Config