Hello,

you can get problems during the installation of the SQL Server of WinCC.
Some reasons for this are known, but described in different FAQs,
that all information are not found at once.
Therefore here a summary:

1. outdated version of the Microsoft Edge browser:

Note on the "20H2" update and SQL server
Subsequent to the installation of the Windows 10 October 2020 update ("20H2"),
there may occur problems with the SQL server Installation. As a consequence,
the WinCC basic installation is disturbed as well.
Cause for the error is an outdated version of the Microsoft Edge browser.
Install the current version (v86.0.622.56+ or higher) to correct the error.

see FAQ:
Which Microsoft Updates ("Security Updates", "Critical Updates" and "Definition Updates")
are recommended for operating SIMATIC WinCC (TIA Portal)?

https://support.industry.siemens.com/cs/de/en/view/109749283

2. Unicode UTF-8 coding

The Windows 10 function update activates the Unicode UTF-8 coding in the Region Settings.

see FAQ:
"How do you ensure that the SQL services can be installed properly after a function
update of Windows 10?2

https://support.industry.siemens.com/cs/de/en/view/109767327

3. multi-core-processors and NUMA
The ratio between logical processors and physical sockets is not a power of 2.
The number of physical cores is not a power of 2.
The total number of CPUs is an odd number.
The setting "NUMA" or "node-interleaving" is enabled in the computer's BIOS

see FAQ:
"What should you watch out for when operating SIMATIC WinCC, WinCC Runtime Professional
or SIMATIC PCS 7 with Microsoft SQL Server on PCs with multi-core or multiple processors?"

https://support.industry.siemens.com/cs/de/en/view/59703368

4. disabled TLS 1.0 and TLS 1.1
For Security reasons you want to disable TLS 1.0 and TLS 1.1 and use TLS 1.2 only on your systems.
If you try to install WinCC V7.4 SP1 without TLS 1.0 installed, The MS SQL Server 2014 setup
show a error message and hold :
“SQL Server was trying to find a TLS protocol that is it supports and that is also supported
by your Windows Server.
This build of SQL Server supports TLS 1.0 and does not support TLS 1.1 and 1.2.
Your Windows Server supports TLS 1.1 and 1.2 and does not support TLS 1.0 . "

Microsoft supports now TLS 1.2 in their Products( SQL-Server, Windows, .NET Framework).
For WinCC V7.4 SP1 you need the TLS 1.0 for the installation, but after it you can deactivate
this TLS 1.0 and use a higher one.
With WinCC V7.5 SP1 the installation is running without TLS 1.0 / 1.1 , here you can use the TLS 1.2 .