New ini files with changes include OpenSim.ini, GridCommon.ini and osslEnable.ini
(note: this only applies to the 15 sept 2018 and beyond)
You will need to use the new ini files and just copy/paste over your settings: database/port/etc
note that any old osslEnable.ini is not compatible with this release as there are changes to how ossl is enabled, etc

all ossl, mod, and lightshare settings are no longer read from [XEngine] and has all been moved into [OSSL] now.

Any specific ossl allows you had configured will need to be added to the new osslEnable.ini

; ==== Settings for MOD and OSSL functions have been moved to the [OSSL] section

this means the following settings now live in osslEnable.ini:

AllowOSFunctions = true
AllowMODFunctions = true
AllowLightShareFunctions = true
OSFunctionThreatLevel = VeryLow

dan

Bump.

Reinstall fresh, copying over your old INI files will really NOT work.
Mind also these latest versions require .NET 4.6 / MONO 5.12

If you enable WARP3D and suffer an extreme delay in startup, try this workaround : https://red-dragon-club.blogspot.com/2018/10/new-opensim-released.html.

One additional thing, I see more and more people running huge VAR's or multi region sims on SQL lite. This is bad practice. This is what opensim wiki has to say on the subject :

By default, OpenSimulator is configured to use the SQLite database. This is very convenient for an out-of-the-box experience since it requires no configuration. However, it's not designed for heavy usage, so if you build very quickly or have more than a few people on your simulator then you will start to see performance issues.
The hint : If you need a clean install anyways, it’s a great time to migrate to MySQL.