Bottom line: the upload step happens in the game

To upload a world to Realms, the actual “Replace World / Upload” action can only be done inside the Minecraft client — Realms is Mojang’s paid subscription service, and the account, subscription, and upload entry point all live in the game. No third-party tool (including TopoBlocks) can log in or upload on your behalf, and we won’t pretend otherwise.

What TopoBlocks helps with is the step before: making sure you have a world file that has the correct structure and imports cleanly, so the upload doesn’t stall on “can’t import / read failed.” Once it’s ready, go into the game, open your Realms settings, and choose “Replace World” or upload.

To decide whether you should use Realms, run your own server, or just share the world file, see Realms vs. running your own server and Put the world on Realms or send the file.

First, get the world into an “importable” shape

When a Realms upload fails, it’s almost never the world itself that’s broken — it’s usually an incorrect archive structure: level.dat isn’t in the root, or the world is wrapped in an extra folder. For this, TopoBlocks’s free on-device diagnosis pinpoints the problem directly; when needed, a simple structure repair (free) outputs a new, importable .mcworld, and it never overwrites your original file — every run produces a new, traceable version.

A few honest notes:

  • Structure repair only fixes file/packaging problems; it won’t fix game crashes, missing mods, cross-major-version incompatibilities, or other non-file issues.
  • Complex corruption goes through advanced repair (¥9/run); before you pay, it shows the problem, the success probability, and the risks, with an automatic refund on failure. Prices are as shown in the app.
  • For the full diagnosis/repair workflow, see the in-depth tutorial Import and repair worlds.

Java or Bedrock? The flavor has to match

Realms comes in two separate flavors, Java Edition and Bedrock, and they’re not interchangeable: a Bedrock Realms only accepts Bedrock-format worlds, and a Java Edition Realms only accepts Java worlds.

If you have a Java world but want it on a Bedrock Realms, you’ll need to convert it first: TopoBlocks offers a one-way Java Edition → Bedrock conversion (pay per use, automatic refund on failure, no promise of 100% lossless — you get a compatibility score before you pay, and an item-by-item change report once it’s done). A Bedrock world cannot be converted back to Java; this step only goes one direction. Once the conversion gives you an importable .mcworld, upload it following the steps above.

Keep a copy before you upload

“Replace World” on Realms overwrites the map currently in the cloud — this is an in-game action, and whether it overwrites is decided by Realms, outside of TopoBlocks’s control. So before you upload, it’s a good idea to export a local backup copy with TopoBlocks, just in case the version you uploaded is wrong and you still have a traceable original to roll back to.

If what you really want is a server that stays online and lets you invite friends, rather than a Realms subscription, take a look at How to host a Minecraft server from your phone — after one-tap startup, you can also safely deploy a generated or repaired world. Deployment runs through “snapshot → verify → atomic swap → health check → automatic rollback on failure,” and likewise never overwrites the source file.