SWPM: ERROR in Selftest. Return code: 3. Connecting to HOSTNAME failed.

You are getting below error message while starting the SAP SWPM tool.

[==============================] - extracting...  done!
INFO: Native locale set to en_US.UTF-8
INFO       2020-09-01 12:44:20.513 (mainThread) [sixxcreate.cpp:347]
********************************************************************************
Initial log directory: /root/.sapinst/HOSTNAME/24634
********************************************************************************


SAPinst build information:
--------------------------
Version:         749.0.82
Build:           1995709
Compile time:    May 07 2020 - 16:53:36
Make type:       optU
Codeline:        749_REL
Platform:        linuxx86_64
Kernel build:    749, patch 832, changelist 1994497
SAP JRE build:   SAP Java Server VM (build 8.1.061 10.0.2+000, Jan 14 2020 
15:48:53 - 81_REL - optU - linux amd64 - 6 - bas2:317685 (mixed mode))
SAP JCo build:   3.0.20
SL-UI version:   2.6.56
SAP UI5 version: 1.60.9
Exe directory: /tmp/sapinst_exe.24633.1598939058

SAPinst process information:
----------------------------
Pid:        24634

ERROR      2020-09-01 12:44:20.844 (root/sapinst) (startInstallation) 
[syxxcniwrapper.cpp:140] id=syslib.network.getInfoFailed 
rrno=FSL-03003 NI::CNIInit::niGetOwnFQDN(iastring::size_type &amp; posOfDomain)
Unable to determine parameter "fully qualified host name". SAPRETURN: 0xffffffff fffffffe

INFO       2020-09-01 12:44:20.845 (root/sapinst) (startInstallation) 
[CSiManagerInterfaces.cpp:2355]
Problem with the DNS configuration: could not determine the DNS domain of host HOSTNAME

INFO       2020-09-01 12:44:20.850 (root/sapinst) (guiWatchdog) 
[CSLPCommunicationServer.cpp:348]
Problem with the DNS configuration: could not determine the DNS domain of host HOSTNAME

INFO       2020-09-01 12:44:21.690 (root/sapinst) (SLPCommunicator) 
[SLPMonitoringStatemachine.cpp:1402]
********************************************************************************
Open your browser and paste the following URL address to access the GUI
https://HOSTNAME:4237/sapinst/docs/index.html
Logon users: [root]
********************************************************************************

=>sapparam(1c): No Profile used.
=>sapparam: SAPSYSTEMNAME neither in Profile nor in Commandline
INFO       2020-09-01 12:44:28.026 (root/sapinst) (startInstallation) 
[SLPSelftestHandler.cpp:156]
********************************************************************************
ERROR in Selftest. Return code: 3
Connecting to HOSTNAME failed.
You can use SAPINST_GUI_HOSTNAME to override the webserver hostname for the GUI.
********************************************************************************

INFO       2020-09-01 12:44:28.026 (root/sapinst) (startInstallation) 
[SLPSelftestHandler.cpp:157]
Full output of selftest:
Connecting to: https://HOSTNAME:4237
    executing: GET /sapinst/slp/whoami HTTP/1.1
java.net.UnknownHostException: HOSTNAME: Name or service not known
Exit code: 3

Solution

Go to SWPM directory and launch the sapinst with the below option,

sapinst SAPINST_GUI_HOSTNAME=localhost

sapinst SAPINST_GUI_HOSTNAME=IP-ADDRESS

Reference

SAP Help
2841879 – SWPM Doesn’t open with error “Exit status of child: 3 Not closing window (Exit State: 3; exitOnError: 0)” on Windows OS
2591258 – ERROR in Selftest. Return code: 3 during start of SWPM Tool (sapinst)