I was getting this error constantly in eclipse:
Errors during build. Errors running builder \"Integrated External Tool Builder\" on project project. Th
In my case, this happened after fiddling with existing builders (e.g. renaming them) and the solution was to restart Eclipse (Neon.3 v4.6.3).
You need to remove missing builders from this location Right click on project->properties->Builders Remove all missing builders
I added this question and answering on my own as I could not find an answer on Stackoverflow and it may benefit someone else
Answer is:
On your project "project", right click -> Properties>Builders Remove the missing builder
Source http://www.eclipse.org/forums/index.php/t/28894/
I was facing the same issue,
"Errors running builder 'Integrated External Tool Builder' on project {PROJECT NAME}"
you must go to your .project file in your work space, and you can put in comment or delete this lines
<buildCommand>
<name>org.eclipse.ui.externaltools.ExternalToolBuilder</name>
<triggers>full,incremental,</triggers>
...
...
</buildCommand>
and after that, you can rebuild your project and it will work correctly.
Reference: https://bugs.eclipse.org/bugs/show_bug.cgi?id=118294
You can follow these steps.
Reference links