Java compiler level does not match the version of the installed Java project facet solution

Today the MyEclipse upgrade to 10, open the original workspace, all the original projects are shown in front of a small fork, there is no error in the code. To view the error message from the problems view, the error message "Description" appears:
Java compiler level does not match the version of the installed Java project facet.
Did not encounter this error before, so Google some, sure enough, many people have encountered the same problem, the solution has the following two kinds:
Scenario 1. At the project name, right-click the property, open the Project Properties dialog box, locate Myeclipse-->project Facets, and set the Java version here to be the same as the project compile level.


Scenario 2. Locate the file named Org.eclipse.wst.common.project.facet.core.xml in the "Project/.settings/" directory, <installed facet= "Java" version= The version value at the "x.x"/> is modified to be the same as the project compile level, save the file, and then refresh the project.

Java compiler level does not match the version of the installed Java project facet solution