It sounds like you have configured your solr_url wrong in your development.ini, so when CKAN tries to contact SOLR on it, it gets a 404.
I suggest you check your solr_url:
grep solr_url /etc/ckan/default/development.ini
which should give you something like solr_url = http://127.0.0.1:8983/solr
for a single SOLR core or solr_url = http://127.0.0.1:8983/solr/ckan-schema-2.0
for multi-core.
To check SOLR is working, try the admin page with a browser, such as elinks:
elinks http://127.0.0.1:8983/solr
and check you get the 'Solr Admin' page. (BTW it's the same URL path for both single and multicore setups). If you are running multi-core, check that the last part of the solr_url matches the schema name of the core you want.