This is usually due to the incorrect construction of your project , which is not declared as a JAVA or PHP type project.
For example, the contents of the. project file in PHP Engineering should work as follows F3.
<?xml version= "1.0" encoding= "UTF-8"?>
<projectDescription>
<name>projectName</name>
<comment></comment>
<projects>
</projects>
<buildSpec>
<buildCommand>
<name>org.eclipse.dltk.core.scriptbuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.php.core.PhpIncrementalProjectBuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.wst.validation.validationbuilder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
<natures>
<nature>org.eclipse.php.core.PHPNature</nature>
</natures>
</projectDescription>
Also, for example, the contents of the. project file for the JAVA Spring Tomcat project are as follows:
<?xml version= "1.0" encoding= "UTF-8"?>
<projectDescription>
<name>projectName</name>
<comment></comment>
<projects>
</projects>
<buildSpec>
<buildCommand>
<name>org.eclipse.jdt.core.javabuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.springframework.ide.eclipse.core.springbuilder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
<natures>
<nature>org.springframework.ide.eclipse.core.springnature</nature>
<nature>org.eclipse.jdt.core.javanature</nature>
<nature>com.sysdeo.eclipse.tomcat.tomcatnature</nature>
</natures>
</projectDescription>