"This project was saved in a newer version of..." when you have the latest version.

Fix Script PowerShell for you project

Add-Type -AssemblyName System.IO.Compression.FileSystem

Get-ChildItem -Filter *.prproj | ForEach-Object {
$in=$_.FullName
$out=Join-Path $_.DirectoryName ($_.BaseName + "_downgrage.prproj")

$fs=[IO.File]::OpenRead($in)
$gz=New-Object IO.Compression.GZipStream($fs,[IO.Compression.CompressionMode]::Decompress)
$r =New-Object IO.StreamReader($gz,[Text.Encoding]::UTF8)
$xml=$r.ReadToEnd()
$r.Close();$gz.Close();$fs.Close()

# БЕЗ третього аргумента – замінює всі входження
$xml = $xml.Replace('Version="44"','Version="43"')

$ofs=[IO.File]::Create($out)
$ogz=New-Object IO.Compression.GZipStream($ofs,[IO.Compression.CompressionMode]::Compress)
$w =New-Object IO.StreamWriter($ogz,[Text.Encoding]::UTF8)
$w.Write($xml)
$w.Close();$ogz.Close();$ofs.Close()

Write-Host "Done $out"
}

Install the Beta version and it will open there.