Unknown error: Unable to build: the file dx.jar was not loaded from the SDK folder!

This error is annoying and seemingly hard to find a way to fix it.

I got it will Eclipse Luna (4.4.1) and the latest SDK and ADT.

After much messing around – I found the way to fix is to remove Android SDK Tools. SDK Platform-tools and Build-Tools (you might not need to remove al three but I tried platform-tools by itself and it didn’t work)tools


and then re-installed them. Restart Eclipse and the error should be gone!