14:08:09.153 [main] WARN root - The provided URL for contextmyContextName does not lead to a valid file

First, there is a missing space between context and its name, second you should show which URL has been provided, e.g.:

14:08:09.153 [main] WARN root - The provided URL 'my/url/' for context myContextName does not lead to a valid file

@@@@

Reproduce: http://logback.qos.ch/manual/contextSelector.html

<env-entry>
<description>JNDI logging context for this app</description>
<env-entry-name>logback/context-name</env-entry-name>
<env-entry-type>java.lang.String</env-entry-type>
<env-entry-value>myContextName</env-entry-value>
</env-entry>

<env-entry>
<description>URL for configuring logback context</description>
<env-entry-name>logback/configuration-resource</env-entry-name>
<env-entry-type>java.lang.String</env-entry-type>
<env-entry-value>unknown.url</env-entry-value>
</env-entry>