Are you trying to play the map on 1.26 where return bug is basically the only problem, or are you playing it on 2.03+ with years of Reforged changes and possible issues?
Can you share steps you tried and where the map fails to load? For example, failure to load in World Editor might lead to different help than if it crashes during loading of scripts, or immediately after gameplay starts
Reforged changed:
- The format of the map header / removed name note at top of MPQ
- The format of the w3i information file that includes info like map name, used version, loading screen, etc
- The format of the .doo file that declares the type and location of all doodads
- The format of w3u, w3a, and other similar Object Editor files that describe custom units and abilities for the map (since August 19, 2022 these are on v3 and have some convoluted attempt to support skin splitting for HD or SD)
- The format of Units.doo file used for World Editor unit information
- The number of available jass natives (many were added)
- The format of all ingame textures and models (dds replaces blp, mdx1200 replaces mdx800)
- The format of sounds for soundsets in the game (now its one table instead of two and has Reforged lip sync data, but this is unlikely to affect your map unless you're doing crazy stuff). All audio files changed to flac instead of wav.
- The format of unit profile TXT data, by adding the UnitSkins file to permit a unit to have a skin type independent from its object type (and so the UnitSkins new profile file contains the related unit definitions now, although obviously we commonly match
hfoo footman behavior to hfoo skin data for model and unit name, etc)
- The number of players in the game -- this means maps which directly referenced Player 13 or Player 16 to access Neutral Hostile and Neutral Passive are now instead going to have those units be owned by Maroon and Violet players or something)
The game pretends very hard that the format of all these things did not change, and tries to back-support your map as if it were not a different format for a different game. But this is a game of pretend and auto conversions on 2.03 -- whereas on a patch such as 1.26 it would load your map as-is from 1.23 or below, but with the difference that return bug is a script error.
Also, removal of return bug on 1.26 to fix a virus exploit failed, and so you can do the same return bug on 1.26 but you have to write a more complicated subroutine to cause the bug -- after you do the map from 1.23 can run the exact same way. This also means any map you play on Patch 1.26 gets administrator access to your computer in a way that will not trigger virus protection, because it will masquerade as if it were the normal Warcraft III game itself.
1.27 and 1.28 are also vulnerable likewise, 1.29 is the first one where I was unable to get old return bug maps to work via the published workaround on Hive.
Edit: A lot of what I mentioned above should not matter for you but if you open your map on Reforged editor and save it again, it should probably forward port the map to the new formats automatically. Without knowing how that process failed for you, or what isn't working, it's difficult to help -- because listing the endless list of arbitrary stuff that changed and
might affect the map as I mentioned above is presumably going to be a waste of time versus resolving targeted issues with the specific map.