Dumb Question: Why do patches break save games?

[Lord Bayushi]

Not really a computer guy, just thought I would ask.

Dumb Question Part Two: If I copy a saved game as a worldbuilder file, then reload it with the new patch as a scenario, will that get around the problem, or would I have to go through and duplicate the map and every individual city, unit, etc. in order to continue a game through a new patch?

Dumb Question Part Three: Is it possible to save a multiplayer game (hotseat in this case) as a worldbuilder file, or open it in worldbuilder in any way?

Thanks for the help.

 

[BeefontheBone]

They don't always break savegames, just fairly often - basically, if something fundamental changes, the data in the saved game will no longer make any sense to the game when it tries to open it with the new files. Some types of changes won't have this effect, but quite a lot do. I doubt you can get round it with what you suggested in part 2, I'd expect it to report the same error when you tried to open the wbs. Regarding part 3, not as far as I know - WB should be diabled in MP.

 

[MagisterCultuum]

Removing anything from the game (like, taking out a unit, building, or promorion) always breaks save games. Schema changes break save games. SDK changes break save games. Major Python changes usually break save games, but minor ones are usually fine. Adding things (units, buildings, promotions, etc) to XML defines or tweaking them slightly without changing the schema is fine. Changing unit art is fine.

I don't think that world builder would get around any of these problems. However, if you really know what you are doing and know exactly what changes were made in the last patch then you could probably open the worldbuilder save in notepad and edit it so that it would be compatible (I think this is beyond my skill level. Well, maybe it isn't, but it would be a slow and tedious process. You should probably ask a scenario maker rather than a modmoder, since it really isn't the same type of skill.)


Normally you can't use worldbuilder in Multiplayer at all. Kael made a debug option allowing it in .25 (to help test OOS erors), but I don't think it exists in .30. Also, when I tried to use it once in a hotseat game (the only kind of Multiplayer game I play) I found that it didn't really work. The menu had the option to enter worldbuilder, but when I selected it nothing happened.

 

[Lord Bayushi]

Thanks for the comments. Anything that is beyond your skill levels are certainly beyond mine, just checking to see if there were any workarounds.
*shrugs*
Oh well.

 

[CyberChrist]

Adding things (units, buildings, promotions, etc) to XML defines or tweaking them slightly without changing the schema is fine.

Hmm no - partly wrong.

Adding or removing any buildings, units, promotions etc. WILL break a savegame from a previous version.

However, you can add and remove fields for each building, unit, promotion etc. without breaking a previous savegame (effectively requiring changes to both the Schema and SDK) - provided a version of these fields are not expected to be present in the savegame file.

Indvidual changes to the various fields wont break a savegame either.

...

Basicly then if a patch includes new buildings, units, promotions etc. then a previous savegame wont work - if patch only tweaks the already existing buildings, units, promotions etc. then a previous savegame might work (and this holds true for any cIV version/mod).

 

[MagisterCultuum]

Removing certainly will, but I'm pretty sure I've gotten away with adding things before (I wonder if the fact that I always add to the end of the xml files helps, since it wouldn't throw off the indexing in the same way)

 

[Nikis-Knight]

It would be a pain to modify a scenario in progress--i.e., do a search and then replace for any unit/promotion, etc. removed. Though if you had the initial autosave you could replay the map without too much trouble, I should think.

 

[MacGyverInSpace]

Sometimes your particular save game might not break, if, for example, none of the removed units have been researched yet, or a certain altered civ is not in your game...

 

[isau]

The most frequent reason I've seen for games failing to load after a patch is a change in the number of elements in an XML document.

The technical reason for this is when Civ IV loads most XML files it creates "space" in memory to store the data (in the form of something called an array). When you save this data, it gets written to the hard drive with a particular length. When you start the game after its been patched, if the length of one of the saved lists is different from the new length defined in the patch, data gets read out of places it shouldn't, and the load fails.

The other major reason loads tend to fail is the creation or deletion of a saved variable. Adding or deleting even one saved variable is 100% gaurantee that the patch will break save games.

Things that tend not to break save games include revising/tweaking existing formulas, adding function calls, and modifying numeric values within an XML file without changing the length--although the latter can cause serious problems in some cases and should be avoided if possible.