Unable to reproduce with 1.35 release. I suspect there is not an issue with the Example skin here, as the page is rendering fine.

Cn you provide more information on what you are seeing in the network tab? I suspect there is an error in the stylesheet itself.

Please subsitute with your own localhost, but tell me if you see any errors in http://localhost:8888/w/load.php?lang=en&modules=skins.example&only=styles&skin=example - ideally copy and paste the text of the error rather than taking a screenshot.

Did you run composer install per the mediawiki install instructions?

@Nasirkhan: Could you please answer the last comment? Thanks in advance!

@Jdlrobson I used tar archive to install mediawiki and i did not run any composer update. I did not see any error on console or network tab. So here I am sharing the some screenshots again

For what it's worth:
I ran into the same problem. The reason seems to be the following with load.php:

[c37b15c693d3a30d06ce5067] /mediawiki/load.php?lang=en&modules=ext.translate|ext.translate.tag.languages|ext.uls.pt|skins.example&only=styles&skin=example   InvalidArgumentException from line 145 of /path/to/mediawiki/includes/resourceloader/ResourceLoaderSkinModule.php: Feature `1` is not recognised
Backtrace:
#0 /path/to/mediawiki/includes/resourceloader/ResourceLoaderFileModule.php(397): ResourceLoaderSkinModule->getStyleFiles()
#1 /path/to/mediawiki/includes/resourceloader/ResourceLoaderSkinModule.php(170): ResourceLoaderFileModule->getStyles()
#2 /path/to/mediawiki/includes/resourceloader/ResourceLoaderModule.php(756): ResourceLoaderSkinModule->getStyles()
#3 /path/to/mediawiki/includes/resourceloader/ResourceLoaderModule.php(704): ResourceLoaderModule->buildContent()
#4 /path/to/mediawiki/includes/resourceloader/ResourceLoader.php(1191): ResourceLoaderModule->getModuleContent()
#5 /path/to/mediawiki/includes/resourceloader/ResourceLoader.php(899): ResourceLoader->makeModuleResponse()
#6 /path/to/mediawiki/load.php(51): ResourceLoader->respond()
#7 /path/to/mediawiki/load.php(38): wfLoadMain()
#8 {main}

Problematic modules: {"skins.example":"error"}
*/
[CSS follows]

I did some debugging, adding some more details around line 145 of includes/resourceloader/ResourceLoaderSkinModule.php:

if ( !isset( self::FEATURE_FILES[$feature] ) ) {
    $tmpstyles = print_r($styles, true);                                                                                                                                                               
    $tmpfeatures = print_r($this->features, true);
    throw new InvalidArgumentException( "Feature `$feature` is not recognised. styles = $tmpstyles, features = $tmpfeatures" );
}

The output suggests there is some mistake with parsing the skin.json file but at that point I gave up and updated to mediawiki 1.35.3 which solved this problem. But still the menu doesn't show up at all (as Jdlrobson mentioned). I just did a local update to 1.36 and now the menu is working. That's a bit sad because I'd prefer to have my production system run with the LTS version and still start using the new skin architecture but that's a different topic I guess...

The output suggests there is some mistake with parsing the skin.json file

Hey @Holybiber can you point me to some code that has that issue so I can help? I suspect the issue is in skin.json in how the features are declared. We supported arrays of features to begin with, but in 1.36 expanded it to allow object declarations. I suspect its a case of switching from array to object or vice versa.

but at that point I gave up and updated to mediawiki 1.35.3 which solved this problem. But still the menu doesn't show up at all (as Jdlrobson mentioned). I just did a local update to 1.36 and now the menu is working. That's a bit sad because I'd prefer to have my production system run with the LTS version and still start using the new skin architecture but that's a different topic I guess...

Have you seen the polyfill listed in https://www.mediawiki.org/wiki/Manual:How_to_make_a_MediaWiki_skin#Building_skins_for_1.35 ? That should support you making use of the new skin architecture for older versions. Let me know if you need any help, by sharing a github issue/phabricator ticket/other site bug tracker where I can help out.

Hey @Holybiber can you point me to some code that has that issue so I can help?

Hi @Jdlrobson, thanks for your comments! Well I didn't try anything more because it seemed this particular issue is solved with mediawiki 1.35.3

And I guess I'll now just go with mediawiki 1.36, that's fine and then all should work as expected.

I'd appreciate some remarks on the needed versions in the introduction of https://www.mediawiki.org/wiki/Manual:How_to_make_a_MediaWiki_skin

I had then tried everything with mediawiki 1.35.3 and the latest commit of Skin Example that still didn't require 1.36 (that requirement was apparently introduced some months ago) but still the menu didn't display at all.
So having a clear remark right at the beginning that version 1.36 is definitely necessary for the new way of skinning would be helpful.

And I don't know about @Nasirkhan but maybe that issue here could be closed then...

I'd appreciate some remarks on the needed versions in the introduction of https://www.mediawiki.org/wiki/Manual:How_to_make_a_MediaWiki_skin

I think https://www.mediawiki.org/wiki/Manual:SkinMustache.php contains the information you need for that. This is linked in several places on that page, but I've added to another section to make sure it's clearer.