Archive for the tag 'troubleshooting'

APR on OpenSuSE and symbol lookup errors

Posted by mark on July 19, 2009 under Technology

OpenSuSE, Apache start: apr_ldap_ssl_init unresolved symbol for no apparent reason

Just a week ago I’ve switched a webserver installation from using files for authentication (.htpasswd and such) to polling user accounts from MySQL tables. This has the advantage of re-using existing user administration (such as in forums), implementing finer policies due to SQL commands or using features such as automatic account expiry (SQL: WHERE ... AND expiry IS NULL OR expriy <= UNIX_TIMESTAMP()).

With Apache 1.3 and even 2.0 I’ve used mod_auth_mysql for this, but since Apache httpd 2.2 mod authn_dbd became usable. Unfortunately the version shipped with OpenSuSE 11.1 was linked against an old MySQL version, therefore I’ve had to compile apr and apr-util for libapr-util1-dbd-mysql again.

Obviously there are more like me (see here for other troubleshooting), as this error seems to occur frequently at starting Apache:

/usr/sbin/httpd2-worker: symbol lookup error: /usr/sbin/httpd2-worker: undefined symbol: apr_ldap_ssl_init

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fixing exceptions of SLF4J and httpunit

Posted by mark on March 10, 2009 under Development

slf4j-exceptions-to-pull-ones-hair

Ever experienced an exception like this? (1)

com.sun.jersey.api.container.MappableContainerException:
java.lang.NoClassDefFoundError: org/slf4j/impl/StaticLoggerBinder

com.sun.jersey.api.container.MappableContainerException:
java.lang.NoClassDefFoundError: Could not initialize class org.apache.commons.httpclient.HttpClient

Or this one? (2)

java.lang.IllegalAccessError: tried to access field org.slf4j.impl.StaticLoggerBinder.SINGLETON from class org.slf4j.LoggerFactory

They’re caused by slf4j, a logger widely accepted as successor to the obsolete Apache commons logging. To be more precisely, by missing (1) or mixed versions of JARs (2). To fix it Read more »

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