Error "failed to get a socket for (null)" after upgrading apache httpd

The symptom: After an regular Debian update, when I tried to start apache, it show me this error:

(22)Invalid argument: alloc_listener: failed to get a socket for (null)
...
Syntax error on line xx of /etc/apache2/ports.conf:

The line was
Listen 80

Status on verification of signed file

Table with Digital Signature Status Values

Counter-signatures and signing a file with multiple certificates

Counter-signing is the action of signing data that includes another signature.

Searching in default maven repository

http://repo1.maven.org/maven2/ is the default repository for Maven 2 & 3, but many times it is hard to find the project artifactId, groupId and version in it.

log4j in maven project

Adding support for log4j is realized via maven dependency. You have to edit pom.xml file, and add these lines: