If I launch the pkg-file, I get the message "The installation failed. The installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.".
This is the log output of /var/log/install.log which reports some signing issues.
I also disabled gatekeeper manually via "sudo spctl --master-disable", but it did not help.
Sep 19 09:55:54 greybox Installer[4206]: Starting installation:
Sep 19 09:55:54 greybox Installer[4206]: Configuring volume "Macintosh HD"
Sep 19 09:55:54 greybox Installer[4206]: Preparing disk for local booted install.
Sep 19 09:55:54 greybox Installer[4206]: Free space on "Macintosh HD": 20.45 GB (20447825920 bytes).
Sep 19 09:55:54 greybox Installer[4206]: Create temporary directory "/var/folders/n2/fpv312vd5xg91ncw_s5f1m5m0000gn/T//Install.42067fNr3f"
Sep 19 09:55:54 greybox Installer[4206]: IFPKInstallElement (1 packages)
Sep 19 09:55:54 greybox installd[1370]: PackageKit: Adding client PKInstallDaemonClient pid=4206, uid=501 (/System/Library/CoreServices/Installer.app/Contents/MacOS/Installer)
Sep 19 09:55:54 greybox Installer[4206]: PackageKit: Enqueuing install with framework-specified quality of service (utility)
Sep 19 09:55:54 greybox installd[1370]: PackageKit: ----- Begin install -----
Sep 19 09:55:54 greybox installd[1370]: PackageKit: request=PKInstallRequest <1 packages, destination=/>
Sep 19 09:55:54 greybox installd[1370]: PackageKit: packages=(
"PKLeopardPackage <file://localhost/Volumes/Server/macOS%20Server%205.2%20beta%20build%2016S1161.pkg#ServerApp.pkg>"
)
Sep 19 09:55:54 greybox installd[1370]: PackageKit: Session UUID file exists - will not overwrite /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/5E3994E6-2688-49F0-8C56-7D96A45AEB96.activeSandbox
Sep 19 09:55:54 greybox installd[1370]: Package: PKLeopardPackage <file://localhost/Volumes/Server/macOS%20Server%205.2%20beta%20build%2016S1161.pkg#ServerApp.pkg> Failed to verify with error: Error Domain=PKInstallErrorDomain Code=105 "The package “macOS Server 5.2 beta build 16S1161.pkg” has an invalid signature." UserInfo={NSUnderlyingError=0x7f9cfbd02220 {Error Domain=NSOSStatusErrorDomain Code=-2147416000 "CSSMERR_CSP_INVALID_CONTEXT_HANDLE" UserInfo={NSLocalizedDescription=CSSMERR_CSP_INVALID_CONTEXT_HANDLE}}, NSURL=file://localhost/Volumes/Server/macOS%20Server%205.2%20beta%20build%2016S1161.pkg#ServerApp.pkg, PKInstallPackageIdentifier=com.apple.pkg.ServerApp, NSLocalizedDescription=The package “macOS Server 5.2 beta build 16S1161.pkg” has an invalid signature.}
Sep 19 09:55:54 greybox installd[1370]: PackageKit: Install Failed: Error Domain=PKInstallErrorDomain Code=105 "The package “macOS Server 5.2 beta build 16S1161.pkg” has an invalid signature." UserInfo={NSUnderlyingError=0x7f9cfbd02220 {Error Domain=NSOSStatusErrorDomain Code=-2147416000 "CSSMERR_CSP_INVALID_CONTEXT_HANDLE" UserInfo={NSLocalizedDescription=CSSMERR_CSP_INVALID_CONTEXT_HANDLE}}, NSURL=file://localhost/Volumes/Server/macOS%20Server%205.2%20beta%20build%2016S1161.pkg#ServerApp.pkg, PKInstallPackageIdentifier=com.apple.pkg.ServerApp, NSLocalizedDescription=The package “macOS Server 5.2 beta build 16S1161.pkg” has an invalid signature.} {
NSLocalizedDescription = "The package \U201cmacOS Server 5.2 beta build 16S1161.pkg\U201d has an invalid signature.";
NSURL = "file://localhost/Volumes/Server/macOS%20Server%205.2%20beta%20build%2016S1161.pkg#ServerApp.pkg";
NSUnderlyingError = "Error Domain=NSOSStatusErrorDomain Code=-2147416000 \"CSSMERR_CSP_INVALID_CONTEXT_HANDLE\" UserInfo={NSLocalizedDescription=CSSMERR_CSP_INVALID_CONTEXT_HANDLE}";
PKInstallPackageIdentifier = "com.apple.pkg.ServerApp";
}
Sep 19 09:55:54 greybox installd[1370]: PackageKit: Running idle tasks
Sep 19 09:55:54 greybox Installer[4206]: install:didFailWithError:Error Domain=PKInstallErrorDomain Code=105 "The package “macOS Server 5.2 beta build 16S1161.pkg” has an invalid signature." UserInfo={NSLocalizedDescription=The package “macOS Server 5.2 beta build 16S1161.pkg” has an invalid signature., NSURL=file://localhost/Volumes/Server/macOS%20Server%205.2%20beta%20build%2016S1161.pkg#ServerApp.pkg, PKInstallPackageIdentifier=com.apple.pkg.ServerApp, NSUnderlyingError=0x600000256c50 {Error Domain=NSOSStatusErrorDomain Code=-2147416000 "CSSMERR_CSP_INVALID_CONTEXT_HANDLE" UserInfo={NSLocalizedDescription=CSSMERR_CSP_INVALID_CONTEXT_HANDLE}}}
Sep 19 09:55:54 greybox installd[1370]: PackageKit: Removing client PKInstallDaemonClient pid=4206, uid=501 (/System/Library/CoreServices/Installer.app/Contents/MacOS/Installer)
Sep 19 09:55:54 greybox installd[1370]: PackageKit: Done with sandbox removals
Sep 19 09:55:55 greybox Installer[4206]: Install failed: The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.
Sep 19 09:55:55 greybox Installer[4206]: IFDInstallController 8B40 state = 8
Sep 19 09:55:55 greybox Installer[4206]: Displaying 'Install Failed' UI.
Sep 19 09:55:55 greybox Installer[4206]: 'Install Failed' UI displayed message:'The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.'.