I have a D8 (8.5.6) installation which I have been trying to upgrade to 8.6 since it came out. It is on a shared hosting account which does not allow drush, so FTP it is. During the database update, it fails and I end up with the proverbial white screen of death. Before delving into detail troubleshooting, I want to disable all the third-party modules, and see if this works. If successful, I want to enable the third-party modules, one by one.
Is that a "good practice" type of approach?
The point is to quickly identify whether it is a contrib module which causes problems are the core install. Normal troubleshooting procedures would follow in any case.