[TYPO3-Solr] Solr Search module gives PHP Fatal Error, but searching works fine

[Hans van Dijk]

Hi all,

I have this strange issue and it seems to have something to do with upgrading from Solr 3.0.1 to 3.1.2 and downgrading from there to 3.0.2
I use TYPO3 6.2.25, TYPO3 ext Solr 3.0.2 and Apache Solr 4.8.1

Searching in the front-end and indexing (scheduler) works fine. With the extension “Solr Admin” everything works fine as well.
In TYPO3 the status report says it can connect to my 4 Solr cores, but when I click on the “Search" module in the back-end of TYPO3 I get this error:
“Core: Error handler (BE): PHP Catchable Fatal Error: Argument 1 passed to ApacheSolrForTypo3\Solr\Domain\Model\ModuleData::setSite() must be an instance of Tx_Solr_Site, null given, called in .../typo3conf/ext/solr/Classes/Backend/SolrModule/AbstractModuleController.php on line 141 and defined in .../typo3conf/ext/solr/Classes/Domain/Model/ModuleData.php line 50"

It seems that only the search module can not connect to the cores??
I have emptied the sys_registry tx_solr record and initialized the cores again and that works perfect, but still the “Search" module gives me the same error!?

Is there someone who has a clue to unravel this Search module error?
TIA

Best, Hans van Dijk