JDT weaving is currently disabled

Question

I just installed Eclipse standard 4.4 Luna, and after installing the Scala IDE and friends I get

JDT Weaving is currently disabled. The Scala IDE needs JDT Weaving to be active,
or it will not work correctly. 

Activate JDT Weaving and Restart Eclipse? (Highly Recommended)

[OK] [Cancel]

Does anyone know how to do this?

Now my comments on this error message

• In general error messages that tell you what to do, but not how to do it are frustrating.
• The [OK] button implies that the dialog will enable it for me, but it does exactly the same as clicking the [Cancel] button. Consequently, the UI design is defective.
• The preferences dialog in Luna does not show anything under JDT or Weaving.
• The help search in Luna for "JTD Weaving" returns too much information to offer any simple solution.
• My search via Google turns up interesting discussion on the problem, but fails to simply state the solution, or if there is one.

https://groups.google.com/forum/#!msg/scala-ide-user/7GdTuQHyP4Q/aiUt70lnzigJ

Groan

Which version of the Scala IDE did you install? This one is advertised as Luna compatible and seems to work for me: scala-ide.org/download/milestone.html#scala-ide-400-milestone-2 – Chloropicrin

There's a issue in STS [1] that points to a regression in Eclipse [2], that is claimed to be fixed in the Integration builds for 4.4. I, however, am still seeing this problem. [1] issuetracker.springsource.com/browse/STS-3762 [2] bugs.eclipse.org/bugs/show_bug.cgi?id=432670 – Erasme

Thanks @Paul, using download.scala-ide.org/sdk/lithium/e44/scala211/dev/site seems to get around the JDT Weaving problem, but now I am having other problems getting my Scala projects to port forward from Kepler to Luna. Ces't la vie – Groan

Originally I used the Scala IDE from Eclipse Marketplace. I guess it takes a while for the marketplace to get updated with the correct versions of things. – Groan

OK, all good now, able to compile and run 2.10 code with 2.11, Luna and Lithium. – Groan

Answer 1

I had the same problem with Eclipse Luna. Your problem might be due to installing the plugin for wrong version of Eclipse.

Did you install Scala plugin from this page: Download the 3.0 Release of the Scala IDE for Eclipse? It is for Juno and Kepler only.

I downloaded the plugin from the link at Download the Latest Nightly Build, using http://download.scala-ide.org/nightly-scala-ide-luna-211x. And it works perfectly now.

Hope this helps :)

Connivent

Answer 2

I also ran into this problem, and similar to the answer above, I solved it by updating scala-ide. The nightly build site didn't have updated plugins. The latest milestone release, however, had everything I needed. You can find the latest milestone releases here:

http://scala-ide.org/download/milestone.html

And the version I am using which is working for me today (and advertised to be working well on Luna) is: http://download.scala-ide.org/sdk/lithium/e44/scala211/dev/site/

Pluri

Answer 3

I managed to resolve it by installing fresh copy of Eclipse Luna with the latest Scala IDE plugin. Now JDT option is enabled and read only.

Radferd

Answer 4

For Eclipse 4.4 use this update site for the Scala plugin:

http://download.scala-ide.org/sdk/lithium/e44/scala211/stable/site

This one works for me in Eclipse 4.4.2.

Pitchdark

Answer 5

I had the same issue, but problem wasn't with version of scala plugin but with the name of directory of eclipse. One of the folders had '!' sign in the name and it made it imposible to enable jdt weaving. When I installed eclipse in another directory with normal signs everything runs ok.

Xylograph