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Launching UAT error: System.ArgumentException: An item with the same key has already been added.

Hi guys, thanks for reading this.
During the phrase of launching, I got the error from the project launcher said : System.ArgumentException: An item with the same key has already been added.

So according to solutions online, here’s what I’ve tried but not work:

  1. Delete Intermediate, Saved, and Config folders;
  2. Search Engine folder with .target files if there’s another copy;
  3. Rename .uproject;
  4. Checked if there’re plugin installed twice with different version;
  5. Checked asset’s name;
  6. Migrate the project to another blank one;
    7.Refresh all the nodes in blueprints.

Any idea or solution will be more than appreciated. Thanks!

I had this error, and it turned out I had got a ‘hot’ patch from a plugin dev, which I applied manually.

In applying it, I moved the old version of the plugin to a renamed folder, but left it in the same hierarchy.

That was the problem. The packing system could see two copies of the same plugin, even though they were in differently named folders. I just deleted the old one, boom.

So, maybe you have exactly that scenario, or something similar?..