You may choose a custom name, but not the name of any vanilla version. json' links to download a client.jar file, and a. Click the 'Download → Client' and 'Download →. Here, you find links to download the version files directly from Mojang's servers.

On the top right of the page, you'll see a box with some informations about the version.

Visit the version page of the version you want to play on the official Minecraft Wiki.(Beware of pirated third-party launchers though, they might steal your login data.) If you can use the updated launcher, or a third party launcher (such as MultiMC), you might want to use those. To work around this issue, you can install versions you want to play manually. It happens because the legacy launcher does seem to have problems with downloading and installing the newer version files. This is an error that occurs only when launching 1.14.4, 19w36a, or versions that have been released after 19w36a. It is recommended to use the updated launcher (legacy or not) instead of using the workaround below.

You find the workaround for this issue that could be used before it was fixed below. If you're not able to launch the 2.x.x launcher, please create a new ticket about that. You can find the download links for it here.

If you're able to launch the updated launcher (2.x.x), it is recommended to update to this one instead.

If your launcher does not automatically update, you can download the updated version (1.6.93) here. A new version of the legacy launcher has been released that solves this issue.

Minecraft legacy launcher windows