Hello Tobias,
You are right, its not a duplicate package at runtime.
I have ran karaf locally to confirm behavior and I could see "is not
instance" errors on all servlets, not only Spring.
It boils down to the spec version shipped by default in Karaf, which is
jakarta.servlet/jakarta.servlet-api/4.0.4.
By installing jakarta.servlet/jakarta.servlet-api/5.0.0 you ship
jakarta.servlet needed by activemq-web, but pax-web (which embeds Jetty
in Karaf) still expects javax.servlet and links to spec 4.0.4. Since
activemq-web is deployed as WAR (WAB) pax web scans web.xml while
runtime parses OSGi headers in WAR manifest which points to
jakarta.servlet;version="[5,6)". You effectively got an incompatible
runtime.
I've got a slightly different failure with later release of pax-web
(11.x), however runtime still keeps track on older one.
Overall you may need a re-assembly of Karaf to pull later release of
pax-web which rely on jakarta namespace. For this I believe its better
to consult karaf mailing list rather than activemq.
Kind regards,
Łukasz
On 7/6/26 19:34, Tobias Hein wrote:
Hi Lukasz,
I'm not sure, if you are right. I don't expect multiple javax.servlet-
packages, because org.springframework.web.servlet.DispatcherServlet is a
jakarta.servlet.Servlet.
Watching all dependencies, that are required in feature:info activemq-
broker, I get the following:
On the one hand, feature:info activemq-broker leads to the dependent
features
activemq-web-console -> war -> pax-web-http-war -> pax-web
At the end, this provides javax.servlet
On the other hand, the bundle mvn:org.apache.activemq/activemq-web-
console/6.2.7/war requires jakarta.servlet
Is this resolvable?
Kind regards,
Tobias Hein
Am So., 5. Juli 2026 um 09:25 Uhr schrieb Łukasz Dywicki <luke@code-
house.org <mailto:[email protected]>>:
Hello Tobias,
While I did not trace issue by myself I suspect that it may be
caused by
multiple javax.servlet packages available at runtime which are in the
end wired to different bundles. Karaf (Pax-Web) uses one, but ActiveMQ
console bundle uses other, leading to two separate Servlet class
instances being present. Effectively Karaf (Pax-Web) refuses spring
servlet, because it uses another (bundle) classloader for specification
classes.
Kind regards,
Łukasz Dywicki
On 7/3/26 17:52, Tobias Hein wrote:
> Hello everybody,
>
> in an OSGi-application running with JDK-21 on apache karaf 4.4.11
I use an
> activemq-broker 6.2.7. This works as expected if I install the
> karaf-feature karaf-broker-noweb.
>
> But I am not able to install karaf-broker, which includes the
> admin-webconsole. First of all there are missing dependencies and
if I
> resolve them manually, I get a mismatch between javax.servlet
(provided by
> karaf) and jakarta.servlet (required by activemq)
>
> Is there any chance to get the webconsole running on apache karaf
in the
> current versions?
>
> How to reproduce in a kind of summary
>
> * download current Karaf OSGi Runtime https://karaf.apache.org/
download.html <https://karaf.apache.org/download.html>
> * unzip and start karaf with ./bin/karaf
> * execute the the following commands in the karaf console
> ** .feature:repo-add activemq 6.2.7
> ** bundle:install mvn:jakarta.servlet.jsp/jakarta.servlet.jsp-
api/3.0.0
> ** bundle:install mvn:jakarta.el/jakarta.el-api/4.0.0
> ** bundle:install mvn:jakarta.servlet/jakarta.servlet-api/5.0.0
> ** feature:install activemq-broker
>
> After that I see the following error in the log-file ./data/logs/
karaf.log
>
> javax.servlet.UnavailableException: Servlet class
> org.springframework.web.servlet.DispatcherServlet is not a
> javax.servlet.Servlet
>
> I installed the jakarta-bundles first, because they are missing
> dependencies of activemq-broker. They are needed for the bundle-
wiring
>
> If you need more details, just ask :-)
>
> Kind regards
> Tobias Hein
>
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