I had the same problem and I think I know why J Solaris does interrupt IO blocked thread which then causes the OutputStreamAppender to catch the IOException in line 218 (version 0.9.24). I actually run version 0.9.18 but this part has not change so I guess it will behave the same way. If we look at http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4385444 InterruptedIOException should not be required by platform specification (sol) And log4j https://issues.apache.org/bugzilla/show_bug.cgi?id=44157 InterruptedIOException ignored by log4j I think it should be solved the same why } catch (InterruptedIOException iioe){ //give the thread a changes to act on interruption and then carry on Thread.currentThread().interrupt(); } catch (IOException ioe) { // as soon as an exception occurs, move to non-started state // and add a single ErrorStatus to the SM. this.started = false; addStatus(new ErrorStatus("IO failure in appender", this, ioe)); } I could not find the jira entry mentioned in this thread therefore I write it here J BTY the jvm option -XX:-UseVMInterruptibleIO does prevent the interruption by solaris but that's only a workaround and not solving the problem ;) Cheers Andy