title: PostgreSQL issue: could not access file "$libdir/plpgsql": No such file or directory
body: <p>I get this exception in PostgreSQL:</p>
  
  <pre><code>org.postgresql.util.PSQLException: ERROR: could not access file "$libdir/plpgsql": No such file or directory
      at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:1721)
      at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1489)
      at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:193)
      at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:452)
      at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:337)
      at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:236)
      at org.apache.commons.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:205)
  </code></pre>
  
  <p>I searched a lot and most solution points to a wrong installation. But this is my test db which has been running without issues for a long time. Also inserts are working. Issue occurs only on select queries.</p>