I've faced this issue many times with eclipse.
Even though we have all the plugins and their dependencies defined correctly, still eclipse shows the errors by saying the prerequisite has to be build first.
It's frustrating since I have not made any changes in the project from the last time.
Okay, so the solution for this is:
1. Identify the root prerequisite plugin which eclipse is complaining about.
2. Close that root plugin
3. Re-open it
4. Do clean build for all projects
Even though we have all the plugins and their dependencies defined correctly, still eclipse shows the errors by saying the prerequisite has to be build first.
It's frustrating since I have not made any changes in the project from the last time.
Okay, so the solution for this is:
1. Identify the root prerequisite plugin which eclipse is complaining about.
2. Close that root plugin
3. Re-open it
4. Do clean build for all projects