Could not resolve placeholder

This error message usually occurs in Spring Framework when a placeholder in the configuration file cannot be resolved.

Placeholders in Spring Framework are typically used to externalize configuration settings from the code, allowing for easy reconfiguration without having to modify the code.

To resolve this error, you should check the following:

1. Make sure that the placeholder is defined correctly in the configuration file, with the correct syntax and spelling.

2. Check that the property file containing the placeholder is on the classpath and is being loaded correctly.

3. Verify that the placeholder value is present in the property file and is spelled correctly.

4. Ensure that the correct configuration file is being loaded and that there are no conflicts with other configuration files.

5. If you are using Spring Boot, make sure that the property file is named correctly (e.g. application.properties for the default configuration file).

Once you have resolved the issue, the application should be able to start up successfully.