Trying to upgrade XWiki Standard Flavor 11.0.3 Installed version from 10.11.2

In the progress, I see the following error:

Extension [org.xwiki.platform:xwiki-platform-distribution-flavor-mainwiki/11.0.3] is not allowed on namespace [null]. Allowed namespaces are: [wiki:xwiki]
class org.xwiki.extension.InstallException: Failed to resolve extension
    at org.xwiki.extension.job.internal.AbstractInstallPlanJob.installExtension(AbstractInstallPlanJob.java:776)
    at org.xwiki.extension.job.internal.AbstractInstallPlanJob.installExtension(AbstractInstallPlanJob.java:309)
    at org.xwiki.extension.job.internal.AbstractInstallPlanJob.installExtension(AbstractInstallPlanJob.java:277)
    at org.xwiki.extension.job.internal.AbstractInstallPlanJob.start(AbstractInstallPlanJob.java:216)
    at org.xwiki.extension.job.internal.InstallPlanJob.runInternal(InstallPlanJob.java:88)
    at org.xwiki.job.AbstractJob.runInContext(AbstractJob.java:236)
    at org.xwiki.job.AbstractJob.run(AbstractJob.java:213)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: class org.xwiki.component.namespace.NamespaceNotAllowedException: Extension [org.xwiki.platform:xwiki-platform-distribution-flavor-mainwiki/11.0.3] is not allowed on namespace [null]. Allowed namespaces are: [wiki:xwiki]
    at org.xwiki.extension.job.internal.AbstractInstallPlanJob.installExtension(AbstractInstallPlanJob.java:886)
    at org.xwiki.extension.job.internal.AbstractInstallPlanJob.installExtension(AbstractInstallPlanJob.java:773)
    at org.xwiki.extension.job.internal.AbstractInstallPlanJob.installExtension(AbstractInstallPlanJob.java:309)
    at org.xwiki.extension.job.internal.AbstractInstallPlanJob.installExtension(AbstractInstallPlanJob.java:277)
    at org.xwiki.extension.job.internal.AbstractInstallPlanJob.start(AbstractInstallPlanJob.java:216)
    at org.xwiki.extension.job.internal.InstallPlanJob.runInternal(InstallPlanJob.java:88)
    at org.xwiki.job.AbstractJob.runInContext(AbstractJob.java:236)
    at org.xwiki.job.AbstractJob.run(AbstractJob.java:213)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

I did this on our sandbox last week with no issues.

Running on Ubuntu with docker. image: “xwiki:11.0.3-postgres-tomcat”

Got around it by changing to “Check for updates on farm” instead of the default.

Indeed, the error says you’re trying to install the Main Wiki Flavor on the whole farm (ie on all subwikis too). The main flavor can only be installed on the main wiki (i.e. xwiki namespace).

Now I don’t understand what this has to do with “Check for updates”. Check for updates will list you all extensions that can be upgraded. Then you should have a drop down to select where to perform the upgrade but the default should be correct.