cvc-elt.1.a: Cannot find the declaration of element 'project'

error: cvc-elt.1.a: Cannot find the declaration of element 'project'

I am getting this error constantly. Whenever I create a project using maven it starts displaying this error. I have even mentioned the 'maven-war-plugin' under plugin tag and then updated and refreshed the project as well.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.myfirstmvcapp</groupId>
  <artifactId>helloworldabc</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>helloworldabc Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <build>
  <plugins>
  <plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-war-plugin</artifactId>
  <version>3.3.1</version>
  </plugin>
  </plugins>
    <finalName>helloworldabc</finalName>
  </build>
</project>

I have Found the Solution to this problem, Thanks to @M.Deinum who commented the solution below the question.

All I did was add https to the link in the tag, instead of http.

here is the previous code:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.myfirstmvcapp</groupId>
  <artifactId>helloworldabc</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>helloworldabc Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <build>
  <plugins>
  <plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-war-plugin</artifactId>
  <version>3.3.1</version>
  </plugin>
  </plugins>
    <finalName>helloworldabc</finalName>
  </build>
</project>

Here is the lastest code, 3 places you need to add https. Below is the working code

<project xmlns="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.myfirstmvcapp</groupId>
  <artifactId>helloworldabc</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>helloworldabc Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <build>
  <plugins>
  <plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-war-plugin</artifactId>
  <version>3.3.1</version>
  </plugin>
  </plugins>
    <finalName>helloworldabc</finalName>
  </build>
</project>