"org.eclipse.wst.validation" has been removed

Same probleme here, there the solution I fix it

• Open the .project file with your prefered text editor.

• delete the node that is about "org.eclipse.wst.validation"

• Close your project

• Open your project

• Launch Maven Update...

Should be good.

Another way to fix it, if you don‘t want to change your .project config (or if you had several projects that must be fixed)

• Close your workspace (or eclipse)

-move out <WorkspaceDir>\.metadata\.plugins\org.eclipse.core.resources\.projects from the workspace directory

-reopen you workspace

• close it again

-move back the .projects dir (say yes to replace questions ? )

• open you workspace

• Launch Maven Update

Should be good

参考以下答复，解决问题：

It appears that deleting the file org.eclipse.wst.validation.prefs in the directory .metadata/.plugins/org.eclipse.core.runtime/.settings (default settings for workspace) or .settings in each individual project will cause the settings for validation to be reset to their original settings. You can then use validation without getting error messages and try resetting the options from there. However, I‘m not sure what combination of settings would cause the problem to reappear. However, if it does, you can repeat the process.