Deploying a maven site to Nexus-3 via https

Ok, so here's the situation:

I have a multimodule Maven project (currently using v3.5.2) which has a large site deployment, some time back I deployed the Maven site (mvn clean site site:deploy) to a Nexus-2.x site repository using simple http.

After migrating to Nexus-3.8.0 I considered to put the whole server bedind a behind a reverse proxy allowing https only, which ran pretty fine so far. Unluckily I'm unable to deploy a site to the new raw repository, which is supposed to hold the sites from my maven project.

The configuration currently looks like this

                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-site-plugin</artifactId>
                <version>3.0.0</version>
                <dependencies>
                    <dependency>
                        <groupId>org.apache.maven.wagon</groupId>
                        <artifactId>wagon-webdav-jackrabbit</artifactId>
                        <version>3.0.0</version>
                    </dependency>
                </dependencies>
                <configuration>
                    <locales>en_US</locales>
                </configuration>
            </plugin>

Running the command above gives me

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-site-plugin:3.7:deploy (default-cli) on project server-policies: Wagon protocol 'https' doesn't support directory copying -> [Help 1]

My site configuration looks like this:

<distributionManagement>
    <site>
        <id>sites-repository</id>
        <url>dav:https://nx3.mydomain/repository/prd-${project.artifactId}</url>
    </site>
    ...
</distributionManagement>

Is there any way to upload sites to a Nexus-3.x repository using https?

No, that's not possible. You have to use http for the site repositories.