Can’t use exists function query in fl of a subquery like below

I have a multiValued stored text field in solr with a lot of text per document. I have a search query “Word1 Word2”. The document is pretty long and contains/might contain the “Word1” many times. The “Word2” is almost/might be at the bottom.

I have a multiValued stored text field in solr with a lot of text per document. I have a search query “Word1 Word2”. The document is pretty long and contains/might contain the “Word1” many times. The “Word2” is almost/might be at the bottom.

I have docs in my index, where every doc has a field popularity, which is a float.

I was using solr 6.6 and now trying to upgrade to 7.3.

I am on Windows Server and using Solr. I use bin/solr start -p 8984 as per this doc here https://solr.apache.org/guide/6_6/running-solr.html which starts the solr correctly. However, as soon as I close the command prompt windows the Solr also stops.

After I installed solr on my machine to test for upgrade implementation to the latest 9.6.1 version I get no error in starting up solr, however when I access localhost:8983 or localhost:8983/solr/#/ I get ERR_EMPTY_RESPONSE.
The logs look like this:
starting logs:

on this section https://solr.apache.org/guide/solr/latest/query-guide/learning-to-rank.html#using-large-models, we are advised to use the DefaultWrapperModel to load large models. But it does not say in which file you have to put the following config: