I had some issue after upgrade the Redirection plugin to 4.0. Redirections were not working anymore and I was unable to add some (with ugly « something went wrong » and a 500 API error code). It turned out that was because an incompatibility of the database upgrade with the SQLite Integration plugin : the database upgrade uses many keywords unknown to SQLite (« AFTER » keyword in ALTER TABLE, « SUBSTRING_INDEX » and « LEFT » functions)
To fix this I fixed the « AFTER » keyword in the SQLite Integration plugin. Here is the corresponding (very simple) Pull Request : https://github.com/aaemnnosttv/wp-sqlite-integration/pull/2
To force the Redirection plugin to update the database I updated the « redirection_options » in the table « wp_options ». In the option_value field you will find the serialized options, and in it the snippet « s:8:"database";s:3:"4.0" » (my database was in version 4.0) ; I updated to the version 2.0 (« s:8:"database";s:3:"2.0" « ) to be sure to get all the database evolutions, but you may start after that.
As the replacement of the missing SQLite functions was more difficult to handle, I updated the Redirection SQL code to update to the new database and executed it manually in my SQLite database :
UPDATE wp_redirection_items SET regex=0 WHERE regex="";
UPDATE wp_redirection_items SET match_url=lower(url) WHERE regex=0;
UPDATE wp_redirection_items SET match_url=substr(match_url,0,instr(url,'?')) WHERE regex=0 AND match_url like '%?%';
UPDATE wp_redirection_items SET match_url=substr(match_url,0,length(match_url)) WHERE match_url like '%/' AND match_url <> "/";
UPDATE wp_redirection_items SET match_url="/" WHERE match_url = "";
Redirection is working fine now, handles redirections properly and let me adds some more again !