The specified product does not exist.

The "The specified JRE installation does not exist" exception typically occurs when there is a mismatch between the Java Runtime Environment (JRE) configuration in your project and the actual JRE installation on your system. Here are a few possible reasons and solutions for this issue:

1. Incorrect JRE configuration in Eclipse:
- Open the project properties in Eclipse by right-clicking on the project and selecting "Properties".
- Go to "Java Build Path" and check the "Libraries" tab.
- Ensure that the correct JRE is selected. If not, click on "Add Library" and select the appropriate JRE.
- Clean and rebuild your project.

2. Incorrect JRE configuration in Tomcat:
- Open the Tomcat server configuration in Eclipse by double-clicking on the server in the "Servers" view.
- Go to the "Java" tab and check the "JRE" section.
- Ensure that the correct JRE is selected. If not, click on "Installed JREs" and add the appropriate JRE.
- Restart the Tomcat server.

3. Multiple JRE installations:
- Check if you have multiple JRE installations on your system.
- Make sure that the JRE you are using for your project is the same as the one you have installed and configured in Eclipse and Tomcat.

4. Environment variables:
- Check if the JAVA_HOME environment variable is set correctly.
- Ensure that the PATH environment variable includes the bin directory of the JRE installation.

5. Reinstalling JRE:
- If none of the above solutions work, try reinstalling the JRE and make sure to configure it correctly in Eclipse and Tomcat.