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Splunk add-on Builder blank page?

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The Splunk add-on builder won't load, it has the header, but the rest is blank. (9.0.3 enterprise + 4.1.1 app)

- Reinstall not helps

-Nothing in splunkd.log, add-on builder logs

- I found this event in web_service.log, but I don't know what should I do with it:

File "/opt/splunk/etc/apps/splunk_app_addon-builder/bin/splunk_app_add_on_builder/solnlib/", line 169, in extract_http_scheme_host_port
raise ValueError(http_url + " is not in http(s)://hostname:port format")
ValueError: splunk."mydomain"."ext" is not in http(s)://hostname:port format

note: I changed the real hostname.

Everything else is ok, all other apps are works fine. I reach the server on  https://splunk."mydomain"."ext":8000  . splunk."mydomain"."ext" format set in server. conf as serverName and in web. conf for mgmtHostPort (with :"port")

Any ideas?


Thanks in advance,



Labels (2)
0 Karma


I had the same issue.
If you look in


index=_internal log_level IN ("error", "warn") splunk_app_addon-builder


You'll find


/opt/splunk/etc/apps/splunk_app_addon-builder/appserver/controllers/ cannot be executed by Python: cannot import name 'soft_unicode' from 'markupsafe' (/opt/splunk/lib/python3.7/site-packages/markupsafe/



Seems the python package markupsafe removed 'soft_unicode' , starting from versions later than 2.0.0.

Solution is to use pip to downgrade


pip3 install --target=/opt/splunk/lib/python3.7/site-packages markupsafe==2.0.0 --force --upgrade


Then restart splunk.
As I'm sure you're aware, this is absolutely a hack...

Happy app-building 🙂

0 Karma
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