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

Question

When I try to run my Android project on Eclipse ADT, I see this in the Console:

[2017-03-24 15:34:41 - Dex Loader] Failed to load C:\Users\jaimemontoya\android-sdks\build-tools\26.0.0-preview\lib\dx.jar 

[2017-03-24 15:34:41 - CouponClub] Unknown error: Unable to build: the file dx.jar was not loaded from the SDK folder!

I am using Eclipse Neon.2 Release (4.6.2):

This is the package configuration I have as seen from the Android SDK Manager:

What I understand from that error is that it failed to load dx.jar because it is trying to load it "from the SDK folder". The message even uses an exclamation mark to say that! What SDK folder is it referring to? I thought in this case "C:\Users\jaimemontoya\android-sdks" would be considered an SDK folder. Do you know where it is expecting to find the "dx.jar" file?

Answer 1

None of the answers helped me only my decision fixed the situation:

Fix is to copy

android-sdk/build-tools/25.0.3/lib 

to the folder

android-sdk/build-tools/26.0.1/lib 

Now all works great!

Answer 2

Eclipse ADT no more support. So Google break backward compatibility with remove two classes from dx.jar.
You can easy fix it.

1. Go to your sdk folder. Navigate to dx.jar from latest build-tools.
   For example build-tools\28.0.3\lib
2. Open dx.jar in any zip archiver.
   I use WinRAR.
3. Navigate to path com\android\dx\command inside archive.
   Here you not see files DxConsole$1.class and DxConsole.class.
4. Now navigate to dx.jar for 25.0.3 or before.
5. Again navigate to com\android\dx\command inside this archive.
   Here you see files DxConsole$1.class and DxConsole.class.
6. Copy it from old dx.jar to new dx.jar. I just drop its from one WinRAR window to another.

All done. Now you can use new dx.jar with Eclipse ADT.

This solution better from replace dx.jar, because you can use new version of the dx.jar.

You need do this steps on every update build-tools.