beta3 = "The Apache Solr search engine is not available. Please contact your site administrator."

Same here.

Same here, but with 1.2
I changed the http lenght on Tomcat, apparently solved the issue, but not completely
The warning appeared when searching a very specific string that corresponded to one specific node... This node was useless, the issue went away after deletion.

I have that problem with 1.2. I found when I restarted solr with the new schema.xml shipped with 1.2, it threw errors on the following:

tint
tfloat
tlong
tdouble
tdate

It looked like the Trie stuff is missing from the solr installation itself...

For now I just commented out all the lines in schema.xml that contained those field types and got solr restarted, but I still have the engine availability issue (although going directly to it at /solr/admin works).

Does upgrading to Solr 1.4 fix the problem? I've only been using this module with 1.4. Haven't had any problems.

I had 1.4 installed already, but I found upgrading to 1.4.1 worked.

I currently using 6.x-2.x-dev with Solr 1.4.1 + Tomcat6 and was having the same issues after adding a date facet. Looks like the date facets make the header size very long and the default attribute is only 4096 bytes, therefore setting the maxHttpHeaderSize to four times the default (16384 bytes) resolved it for me.

As per http://drupal.org/node/443980, for anyone using solr+tomcat, look for the file server.xml

--Add the maxHttpHeaderSize & URIEncoding attributes to the Connector port="8080" or whichever port that you are using, so it looks something like this.

<Connector port="8080" protocol="HTTP/1.1" 
     				maxHttpHeaderSize="16384" 
     				connectionTimeout="20000" 
     				redirectPort="8443" 
               URIEncoding="UTF-8"
   />          

--restart tomcat and flush caches.

Regards,

KH

The solution from http://drupal.org/node/443980 also worked for me using a non-tomcat server. Follow the jetty instructions. Thanks!

subscribing.

Seems to be about config issues. Support request, then.

probably dup of other URL length issues