Plugin Activation Error with solr 5.1.0

I’m trying to activate the plugin and I get this error:

solr 5.1.0 WordPress 4.2.1 (NO war file deployment)

Solr HTTP error: OK (500) {“error”:{“msg”:”Ping query caused exception: Bad contentType for search handler :text/xml; charset=UTF-8 request={q=solrpingquery&json.nl=flat&omitHeader=true&wt=json&echoParams=all&distrib=false}”,”trace”:”org.apache.solr.common.SolrException: Ping query caused exception: Bad contentType for search handler :text/xml; charset=UTF-8 request=

Tests:

https://192.168.3.18:8984/solr/wordpress/admin/ping?action=status
<response>
<lst name=”responseHeader”>
<int name=”status”>0</int>
<int name=”QTime”>0</int>
<lst name=”params”>
<str name=”action”>status</str>
<str name=”echoParams”>all</str>
<str name=”q”>solrpingquery</str>
<str name=”distrib”>false</str>
</lst>
</lst>
<str name=”status”>enabled</str>
</response>

Test with Solarium examples

Solarium library version: 3.2.0 –
{“endpoint”:{“localhost”:{“host”:”192.168.3.18″,”port”:8984,”path”:”\/solr\/wordpress”}}}
{}

Fatal error: Uncaught exception ‘Solarium\Exception\HttpException’ with message ‘Solr HTTP error: OK (500) {“error”:{“msg”:”Ping query caused exception: Bad contentType for search handler :text/xml; charset=UTF-8 request=

Directory rights:
drwxr-xr-x 7 www-data www-data 4096 May 4 12:56 .
drwxr-x— 10 www-data www-data 4096 May 4 12:56 ..
-rw-r–r– 1 www-data www-data 11952 Apr 25 20:34 ajax_solr_services.php
-rw-r–r– 1 www-data www-data 2559 Apr 25 20:34 autocomplete.php
drwxr-xr-x 3 www-data www-data 4096 May 4 12:56 classes
-rw-r–r– 1 www-data www-data 26716 May 4 14:34 class-wp-solr.php
-rw-r–r– 1 www-data www-data 55 Apr 25 20:34 composer.json
-rw-r–r– 1 www-data www-data 4510 Apr 25 20:34 composer.lock
-rw-r–r– 1 www-data www-data 1048648 Apr 25 20:34 composer.phar
drwxr-xr-x 2 www-data www-data 4096 May 4 12:56 css
-rw-r–r– 1 www-data www-data 37134 Apr 25 20:34 dashboard_settings.php
drwxr-xr-x 2 www-data www-data 4096 May 4 12:56 images
drwxr-xr-x 2 www-data www-data 4096 May 4 12:56 js
-rw-r–r– 1 www-data www-data 8337 Apr 25 20:34 readme.txt
-rw-r–r– 1 www-data www-data 7792 Apr 25 20:34 securecookie.php
-rw-r–r– 1 www-data www-data 10151 Apr 25 20:34 solr_services.php
drwxr-xr-x 5 www-data www-data 4096 May 4 12:56 vendor
-rw-r–r– 1 www-data www-data 6716 Apr 25 20:34 wpsolr_search_engine.php

———————————————————————–
Second test to solr 4.9 instance:

Working OK.

https://www.ads-software.com/plugins/wpsolr-search-engine/