Value cannot be null. Parameter name: path1

When I try to add Qt version, I get the following:

== Qt Visual Studio Tools version 2.7.1 (rev.8)

Initialized in: 566.72 msecs
Main (UI) thread: 78.66 msecs

— qmake(415064): started V:\QT\OFFICIAL_CLEAN\QT-EVERYWHERE-SRC-5.15.2-X64\QTBASE\bin\qmake.exe
— qmake: Querying persistent properties
— qmake(415064): exit code 0 (45.47 msecs)

Value cannot be null.
Parameter name: path1

Stacktrace:
at System.IO.Path.Combine(String path1, String path2, String path3)
at QtVsTools.Core.QMakeConf..ctor(VersionInformation versionInfo, QMakeQuery qmakeQuery)
at QtVsTools.Core.VersionInformation.GetQMakeConfEntry(String entryName)
at QtVsTools.Options.QtVersionsPage.SaveSettingsToStorage()

Here is the video: https://youtu.be/DYG_PTlNqNc

Also, I lost all my previous Qt libs when trying to add new ones.
Please advise how to do it manually, because it's urgent for me.