I found a world I wanna play on my old computer and it just says "must be converted" where the version number usually is. I don't know what version it is, and I would like to play on this world in the proper version so I don't risk breaking it. Is there anyway to check this worlds version number??
By the way, I checked when Minecraft started saving the world version in its saves and it seems to have started doing so in 15w32a.
If you downloaded the world from the Internet, then see if the version is stated on the page you downloaded it from. Otherwise, you *could* deduce the version from the world files (e.g. whether the terrain is saved in the Anvil or MCRegion format, whether the players are stored in /players/<username>.dat or /playerdata/<uuid>.dat, whether advancements and statistics are saved in the world, whether certain blocks, entities, or structures are present in the world), but doing so would probably take a lot of effort.
As far as I know, "must be converted" means the world was created or last played prior to 1.2.1, which will display this message for older worlds (with .mcr region files instead of the newer .mca files). All newer versions automatically convert any older data, with non-versioned worlds displayed as "unknown"; even 1.13+ lets you simply load a world without using the "optimize" feature (which converts all chunks at once to reduce lag), with the exception of pre-Anvil worlds due to the different file format (though 1.13's format is more different from 1.2.1-1.12.2 than 1.1-1.2.1), which have always required a mandatory complete conversion on first load.
As far as loading the world goes, you could make a copy and try loading it in 1.15.2, unless you can't select it (I'd be surprised if they still have a built-in MCRegion-Anvil converter, I thought it was removed sometime after 1.6.4, which even creates a "level.dat_mcr" file, which is a backup of level.dat after being converted from MCRegion, when you create a new world even though nothing had been converted; this file is no longer created though). It might be better to convert it in 1.6.4 since prior to 1.2.1 the game didn't save biome data with the world and if the world was created in say, 1.1, landmasses and oceans will be the same (in fact, 1.2-1.6 have a hidden world type* that replicates 1.1 world generation by omitting jungles, the only attempt Mojang ever made to preserve old worlds so they wouldn't get chunk borders when loading new chunks). It is also possible to use MCEdit to change the biomes after it is converted; this requires using a version no later than 1.12.2 since MCEdit doesn't support 1.13+.
Note that you should not load a world from 1.6.4 or earlier in 1.7-1.12 unless you go around and load all chunks since you'll get missing chunks when converting it to 1.13+, as described in this thread. (I don't know if 1.7 properly sets the "LightPopulated" tag when converting a world; chunks that get deleted have this tag present but set to false).
In any case, if you just want to load the world and not update it to newer versions you can look at the dates of the files and compare them to the release dates of different versions, it is also possible to use NBTExplorer to open level.dat and convert the "LastPlayed" time to a date (use this converter). Also, be sure to create a new profile with a separate game directory - versions prior to 1.6 are especially prone to crashing when trying to load settings saved by newer versions, and otherwise they will get reset.
*For whatever reason this world type, called "default_1_1", still exists in modern versions (up to at least 1.12, not sure about 1.13+) and breaks hot climate zones, which are replaced with the 1.1 biome list (this means deserts will be much rarer and savannas nonexistent); you'll want to use NBTExplorer on the converted world to make sure that the "generatorName" is "default" and the "generatorVersion" is 1, setting them to these if not.
I found a world I wanna play on my old computer and it just says "must be converted" where the version number usually is. I don't know what version it is, and I would like to play on this world in the proper version so I don't risk breaking it. Is there anyway to check this worlds version number??
What version are you running?
The version display was added relatively recently, so old worlds won't have the version number saved in the file.
I'm running 1.15.2 and under the world description it says "must be converted".
Yeah, then it's probably a world created before the version info was added to each world.
is there anyway to know for sure though?
By the way, I checked when Minecraft started saving the world version in its saves and it seems to have started doing so in 15w32a.
If you downloaded the world from the Internet, then see if the version is stated on the page you downloaded it from. Otherwise, you *could* deduce the version from the world files (e.g. whether the terrain is saved in the Anvil or MCRegion format, whether the players are stored in /players/<username>.dat or /playerdata/<uuid>.dat, whether advancements and statistics are saved in the world, whether certain blocks, entities, or structures are present in the world), but doing so would probably take a lot of effort.
alright thanks. I may be able to define a version of the world with this info.
As far as I know, "must be converted" means the world was created or last played prior to 1.2.1, which will display this message for older worlds (with .mcr region files instead of the newer .mca files). All newer versions automatically convert any older data, with non-versioned worlds displayed as "unknown"; even 1.13+ lets you simply load a world without using the "optimize" feature (which converts all chunks at once to reduce lag), with the exception of pre-Anvil worlds due to the different file format (though 1.13's format is more different from 1.2.1-1.12.2 than 1.1-1.2.1), which have always required a mandatory complete conversion on first load.
As far as loading the world goes, you could make a copy and try loading it in 1.15.2, unless you can't select it (I'd be surprised if they still have a built-in MCRegion-Anvil converter, I thought it was removed sometime after 1.6.4, which even creates a "level.dat_mcr" file, which is a backup of level.dat after being converted from MCRegion, when you create a new world even though nothing had been converted; this file is no longer created though). It might be better to convert it in 1.6.4 since prior to 1.2.1 the game didn't save biome data with the world and if the world was created in say, 1.1, landmasses and oceans will be the same (in fact, 1.2-1.6 have a hidden world type* that replicates 1.1 world generation by omitting jungles, the only attempt Mojang ever made to preserve old worlds so they wouldn't get chunk borders when loading new chunks). It is also possible to use MCEdit to change the biomes after it is converted; this requires using a version no later than 1.12.2 since MCEdit doesn't support 1.13+.
Note that you should not load a world from 1.6.4 or earlier in 1.7-1.12 unless you go around and load all chunks since you'll get missing chunks when converting it to 1.13+, as described in this thread. (I don't know if 1.7 properly sets the "LightPopulated" tag when converting a world; chunks that get deleted have this tag present but set to false).
In any case, if you just want to load the world and not update it to newer versions you can look at the dates of the files and compare them to the release dates of different versions, it is also possible to use NBTExplorer to open level.dat and convert the "LastPlayed" time to a date (use this converter). Also, be sure to create a new profile with a separate game directory - versions prior to 1.6 are especially prone to crashing when trying to load settings saved by newer versions, and otherwise they will get reset.
*For whatever reason this world type, called "default_1_1", still exists in modern versions (up to at least 1.12, not sure about 1.13+) and breaks hot climate zones, which are replaced with the 1.1 biome list (this means deserts will be much rarer and savannas nonexistent); you'll want to use NBTExplorer on the converted world to make sure that the "generatorName" is "default" and the "generatorVersion" is 1, setting them to these if not.
TheMasterCaver's First World - possibly the most caved-out world in Minecraft history - includes world download.
TheMasterCaver's World - my own version of Minecraft largely based on my views of how the game should have evolved since 1.6.4.
Why do I still play in 1.6.4?