Legacy launcher can no longer start Minecraft

I am having the exact same problem.  Loads fine in everything except for 1.14.4
I cannot update the launcher because I am running Windows Vista Home Premium SP2 64bit

I'm using Ubuntu 16.04 and I just can't launch 1.14.4 on my computer. Same problem where it is stuck on preparing. I have to use the old version launcher since apparently the new one says that I couldn't connect to internet even though it works fine and it also makes me play offline.

I found a new article that says he used the new launcher and it worked fine when he switched so most likely the 1.14.4 is only allowed to work on the new launcher. Don't hold me accountable for that, it's just a theory but most likely Mojang or Microsoft or whoever is in control may have made the files only work for certain launchers.

@Julian As a stopgap I am using the MultiMC launcher. Although it is not a Mojang launcher it seems to work fine, it is free and available for all platforms. Once you have downloaded and installed it, copy your saved worlds into the appropriate place, login with your Mojang userid and away you go.

I will certainly check it out.

Thanks for letting me know.

It appears that this issue is caused by "1.14.4.json" file formating being broken and obfuscation maps entries now being included in the 1.14.4.json file.

Reformating the "1.14.4.json" file with a json editor and removing the obfuscation maps entries then adding this fixed json as a custom version seems to fix it.

Hm, I can't find the 1.14.4.json file with a fresh .minecraft folder.

@Conor Garland, @Marc Larue  The first thing I tried was deleting the 1.14.4 download folder to force a fresh download, this had no effect. The launcher was unable get a fresh download because the error occurs before it gets that far.

@Robert Bowles, @Marc Larue

Download the original "1.14.4.json" file and the 1.14.4 Client here: https://minecraft.gamepedia.com/Java_Edition_1.14.4 then reformat it.

What is an obfuscation map entry? By reformat, do you mean adding whitespace characters?

I can attest to this happening on 3 different computers of mine.  Two have different versions of GNU/Linux (Trisquel on one, xubuntu on another) and one is a Windows machine (Win7).  They all stopped working simultaneously just the other day specifically for 1.14.4, all other versions still work.

I am getting the exact same errors as the original poster.

If any of the advanced users here have figured this out and could clue us in on what reformatting json files is, and what obfuscation map entries are, that would be great.

I suspect that it is something more to do with the launcher version than any file, because the error happens before you even try to load 1.14.4.  And it doesn't effect the newer launcher that has the built in JRE that MS puts out.

@ConnorGarland @violine1101 can you be more specific? Do you mean the client_mappings and server_mappings nodes on the 1.14.4.json, and that we should manually remove them? I see that those are the new nodes that were added.

I removed the old and installed the new launcher using the .tar file (not the one from the Linux Mint Software Manager, which crashes while opening the launcher).  Seems to work fine now.  Once I figured out that I could change from a snapshot to 1.14.4, I can get to my server again.  So for me, the problem was resolved by upgrading to the new launcher. 

I have the same issue on Xubuntu 16.04.6 LTS.

My issue was closed as duplicate of yours

https://bugs.mojang.com/browse/MCL-11997

So I tried diffing the old and new 1.14.4.json

The only difference was the assetIndex which in turn points to a different 1.14.json

Those json in turn had some new language json files...

Can @violine1101 clarify what she means by "obfuscation maps now being included in the version manifest" or @Conor by "reformat"?

I tried "reformatting" the json in a viewer and copying that into the 1.14.4.json file and it didn't work.
 

Update to the new launcher.

Why, Java Minecraft is Java, why bundle it in an executable?

For anyone curious (like I was) the reason this is happening is that the legacy launcher installed to /opt/minecraft (least when I originally installed it via the Debian package). The new launcher (installed the same ) places files in /opt/minecraft-launcher.

At the time I (and probably many others) made a symbolic link to the minecraft.sh script. By doing so no matter how many times I upgraded I always ran the old version. I (and likely others) never thought this is was problem because us Linux folks are used to never having updates to programs especially with past MS history (imagine the egg on my face).

I fixed the problem by downloading the latest Debian package from the download page, Installed it, and re-pointing my symlink to the new executable:

ln -s /opt/minecraft-launcher/minecrafte-launcher /usr/local/bin/minecraft

Same problem here, same logs, and not an option to use the native launcher, I cannot upgrade the underlying Linux, and the native launcher won't start (CXXABI one version too old).

Will the old Java Launcher 1.6.89-j be upgraded? Thanks!

@Devin Weaver and others. Thanks to all the contributors to the comments. So far I have found two alternatives that work for me (Linux Devuan Ascii / Debian Stretch) which I summarize here:

Official Launcher: Following Devin I deinstalled/reinstalled the newest version of the official launcher, making sure to install any unmet dependencies. First download the deb, then (for Debian-like systems):

1. sudo dpkg -i Minecraft.deb         # may give missing dependency errors

2. sudo apt-get -f install                            # forces installation of missing dependencies

One snag I met was there seems to be no way to configure Java in the new launcher, so I had to re-configure the default Java at the system level (annoying as I have about 8 different Javas on one of my boxes).

Unofficial Launchers: YMMV but I found MultiMC worked out of the box but is fiddly to get used to because it has so many powerful options. It is available for Linux Mac and at least some flavours of Windows.

So the workaround is to use another launcher or upgrade to the new one? @Devin Weaver - Your Launcher was installed? I just run mine from a Minecraft.jar file and don't have any other files anyware else that pertain to it. I run it the same way on the Windows 7 machine as well.

I installed the official launcher as many are suggesting. Unfortunately, my Dell XPS-13 "Developer Edition" - which came with Ubuntu 14.04 pre-installed, several years ago - fails to launch the new launcher with this error:

minecraft-launcher: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.20' not found (required by minecraft-launcher)
minecraft-launcher: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `CXXABI_1.3.9' not found (required by minecraft-launcher)
minecraft-launcher: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.21' not found (required by minecraft-launcher)

So it seems I have a fun-filled weekend of Ubuntu distribution upgrade in my future? Or a new laptop purchase. At any rate, would be nice to have a minimum Ubuntu version listed on the downloads page.

A work-around for this would be great, seems very much like a programmer error "duplicate key" - not an intentional bug to discourage stealing.

Just to add my 2 cents:

 If you do a diff on 19w36a.json & 19w35a.json you can see that 2 new subsections were added to the downloads section called "client_mappings" and "server_mappings".  Those two are most likely the culprit for the duplicate key error.

If anyone is curious enough you can find links to those files @ https://launchermeta.mojang.com/mc/game/version_manifest.json

 So this 'bug' of requiring an additional txt file was introduced with snapshot 19w36a on 2019-09-04 and it also affects release 1.14.4 because it was added retroactively to that version on the same day.  That's not how such a thing should be handled normally, imho the next higher version should've introduced it to the release branch. Because of this it actually does sound more like an anti piracy feature to me. 😉

It is not an anti-piracy feature, and the version has not been changed retroactively per se. In layman's terms, this 'manifest' is making modders' lives easier. That's why they've been released. Apparently the old launcher does not know how to handle this new information.

To anyone who has this bug I can only give the advice to give the new launcher a try, or alternatively use a third-party launcher (such as MultiMC; beware of pirated third-party launchers though, they might steal your login data).

If those don't work, make sure that you're running the latest version of the legacy launcher, which is 1.6.91-j. If you're still on an old version of the legacy launcher and the launcher doesn't auto-update to a newer version of the legacy launcher, try this link to download it: https://launcher.mojang.com/mc/launcher/jar/fa896bd4c79d4e9f0d18df43151b549f865a3db6/launcher.jar.lzma. The wiki only says that there have been unknown changes in this version, so I don't know if that actually changes anything significant, but it still might be worth a shot.

If that doesn't work either, chances are your computer does no longer meet the minimum system requirements needed to run Minecraft and is no longer supported by Mojang. Specifically, Linux 32-bit systems are no longer supported by Minecraft if I am informed correctly.

As a workaround (do this at your own risk), you should be able to play 1.14.4 as normal by launching 1.14.4 Pre-Release 7. That version is identical to 1.14.4 in every aspect but the name and the fact that it does not have obfuscation maps. You can't play multiplayer on 1.14.4 servers with that version, though.

I cannot comment on whether this issue will be fixed by Mojang as I am unsure whether the legacy launcher is supported anymore. A Mojang employee will need to clear that up.

Can I get a refund?

@[Mod~violine1101]
"To anyone who has this bug I can only give the advice to give the new launcher a try"
I would give it a try, but how can I use the "launcher.jar.lzma" in an existing installation of Minecrafrt in (X)ubuntu?
I made an backup of the "saves". How can I start the game?
Thank you

Can I get a refund?

Don't know, ask that question to customer support. If you can play older versions of the game, probably not.

I would give it a try, but how can I use the "launcher.jar.lzma" in an existing installation of Minecrafrt in (X)ubuntu?

Unzip it and run the jar file in it. It's the latest version of the legacy launcher. I cannot guarantee that it'll work.

@[Mod~violine1101]
running the jar-file:
Minecraft Launcher 1.6.91 is able to be executed, but the error seems to be the same
"[15:54:51 FATAL]: Unhandled exception in thread Thread[pool-2-thread-2,5,main]"
The "Preparing..." message on the button stays grey and don't disappear.
I would be really happy to continue playing the payed game, to which person can I write?
Thanks a lot for your help.

edit: typos

For technical support, please visit this link: 💬 Community Support

I'm running version 1.6.91-j on windows XP, and get the same error now since both 19w36a and 19w37a. So updating the legacy launcher to its latest version will not help.

@[Mod] violine1101 :
"For technical support, please visit..."

thanks a lot

I can confirm it is possible to run these snapshots (at least in my winXP 1.6.91-j setup) if you install them manually with a custom name (just like a modded version). Workaround will be added to the description

As @unknown already said, we've found a workaround, which I've now added to the description of this ticket. If you need support with installing a version manually, please post a comment in the Reddit thread that I created for support with this issue.

So is gson trying to parse the mapping files?

Just stop obfuscating the game instead?

The issue has been fixed in a future version of the (legacy) launcher by slicedlime. Please be patient as they are releasing this new version soon.

@Jack
"... as they are releasing this new version soon."
I was playing 2 years on my machine and never did any launcher/gameupdates "manually", but only with the paket manager or "sudo apt...". I even can't remember how I installed the game.
So I'm interrested where I can get (later/soon) this updated launcher.
Can you confirm please that the use of the new launcher will be like here described?
https://bugs.mojang.com/browse/MCL-11993?focusedCommentId=582137&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-582137

The updated version has now been released. The version you are looking for is 1.6.93, and the native launcher executable should automatically update you to it.

 
If you need to download it manually for some reason, you can do so here. I do highly suggest you migrate away from that flow however - it is unsupported and might not work in the future.

Thanks a lot! It works on my platform now.

Ok, can you explain what was wrong?

 /Just curious

@slicedlime
thanks for the fix.
I bought the game 2017 (running on Xubuntu 64bit) and I was guided officially to use the legacy launcher.
You suggest to migrate. Do you mean the "2.0 branch of the launcher", I heard now on reddit the first time of this.
Where do I get it?

@unknown All the main downloads are here: https://www.minecraft.net/en-us/download/alternative/

@slicedlime.
Thanks, I'll have a try

The new launcher @slicedlime posted seems to work, but the old bootstrap (Minecraft Bootstrap v5) seems to download an old version of the launcher (1.6.89-j) from https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma . Can you fix this?

The old bootstrap is no longer supported.

@slicedlime Thank you, that fixed it!

For anyone still having problems.

1. You need to change how you start Minecraft. I previously started it via a "Minecraft.jar". Now you have to use a desktop file that runs sh -c "java -jar ~/.minecraft/launcher.jar"

2. You need to replace the launcher.jar in your .minecraft folder with the launcher.jar linked by slicedlime here

Can confirm fix works 😃
I am thankful that it works now, as Im not able to install the newer launcher on my chromebook

@unknown What prevents you from installing the new launcher? Have you reported a bug about that?

@slicedlime I reported MCL-12019, which prevents me opening the new launcher.

I went to /home/username/.minecraft/versions
created new dir /home/username/.minecraft/versions/1.14.4-fix
dowloaded the client and json files as described to the new dir
renamed them to 1.14.4-fix.jar and 1.14.4-fix.json
edited the json file, vi 1.14.4-fix.json did search for id, and altered that to be "id" : "1.14.4-fix"  (note was like the 5th id found after uid uuid ...)
followed this up by finding downloads, removed "downloads" : { <tons of stuff { more stuff} stuff {more stuff} ... }     ## between those {} were like 3 sets of other curly braces, sha ... URL, etc, seemed like over 100 characters total.

Launched - and NO sign of my 1.14.4-fix!
tried again, same

Went and downloaded the launcher file mentioned, still not luck

Repeated all the steps again - sadly the same result. Please tell me if I've done wrong.

Idea 1, just put out the files together as a download so people can just unzip them in the versions directory (and then move the working launcher if that's really necessary). I'm not the only one finding this editing of the file to be difficult. Please step up a bit to make this fix more direct. If you all have done the above edit to the json file then please just share a link here to that file with what ever name you've chosen for the ID. 

Sorry if I'm being too blunt but I really felt like I've been patient thinking a fix would be out after a week or so ( I've worked in IT for over a decade so I know how it can be sometimes) but this is dragging on too long. This problems been going on for WEEKS, maybe a month or more now. At some point the server I've played on for almost a year will let my claims expire simply because I can't log in! 

I'll check back tomorrow, thanks in advance! Other than this I've had a great experience with Minecraft, I know it can be cleared up. Thanks again.

Ken J, just download launcher version 1.6.93 [here|https://launcher.mojang.com/v1/objects/eabbff5ff8e21250e33670924a0c5e38f47c840b/launcher.jar,] and then you won't have to do anything with 1.14.4-fix (at least it worked for me).

Out of curiosity, is there any way to continue with the "workaround" fix? Albeit unsupported I'm attempting to install and play Minecraft on a Windows XP system. I can't use 1.6.93 because it requires Java 8, which is incompatible with Windows XP, and the new launcher simply fails to run ("Unable to start Minecraft Runtime Environment" error keeps popping up).I can't seem to get the "fixed" version showing in the launcher settings. (I should mention I am trying it on 20w13b.)

@EarthToAccess I have no idea if Win XP is supported anymore by anyone, it went EOL several years ago. I think your best bet would be to install a more modern OS. If you can't stomach recent offerings of Windows or there are performance issues with them on your hardware, I can personally recommend some flavour of Linux, which I have been using for my computing needs exclusively for the last 12 years. Minecraft JE runs fine on that. As a 'beginner' distribution, you can do a lot worse than Ubuntu which has a vibrant user base and online support.

Yea, I know. I personally have been using Ubuntu for a while and I've got a Windows 10 computer, I'm just messing with Windows XP on a virtual machine and wanted to see if Minecraft runs well enough on it. I'm fairly certain it would, but I can't get it to actually open because of the launcher issue. Using new software etc. is definitely viable as I already am using said software and hardware, I just wanted to know if it was possible so I could potentially mess with things.