Invalid Property Reference Spring Boot

The "invalid property reference" error in Spring Boot is commonly related to the Spring Expression Language (SpEL) trying to resolve a property or method on a null object, or it can be due to trying to bind properties from the application.properties or application.yml file to a class field but with incorrect references. In this post, we will provide solutions for this error.

Causes

Invalid SpEL Expression

If you're using SpEL within your Spring components to refer to properties, and there's an issue with the expression.

@Value("#{someBean.someProperty}")
private String someValue;

The above expression assumes that a bean named someBean exists, and it has a property named someProperty. 

Incorrect Property Name in Configuration

When binding properties from application.properties or application.yml to a class, if the property doesn't exist or is named incorrectly, it can result in this error.

@Value("${custom.property.name}")
private String propertyName;

Ensure that custom.property.name exists in your application.properties or application.yml file.

Wrong Configuration Property Prefix

When using @ConfigurationProperties with a prefix, ensure that the prefix matches the structure in the properties or YAML file. 

Nested Properties in POJO

When binding nested properties, ensure the parent object is initialized, or Spring Boot might not be able to bind child properties, leading to this error. 

Data Type Mismatch

The property in the properties or YAML file might be of a different data type than the field in your class. For instance, trying to bind a string value to an integer field.

Solutions

Check SpEL Expressions

Make sure that any SpEL expressions you're using are valid. If you're referring to a bean, ensure it exists in the context and has the correct properties or methods you're referencing. 

Verify Property Names

Ensure the property you're trying to bind from the configuration file exists and is spelled correctly.

For example: when binding properties from application.properties or application.yml to a class, if the property doesn't exist or is named incorrectly, it can result in this error.

@Value("${custom.property.name}")
private String propertyName;

Ensure that custom.property.name exists in your application.properties or application.yml file.

Correct Configuration Prefix

If using @ConfigurationProperties, double-check the prefix to ensure it matches your configuration structure. 

Initialize Nested Objects

If you have nested configuration properties, ensure the parent objects are initialized either by providing a default constructor or initializing them manually. 

Ensure Data Type Consistency

Make sure the data types in your configuration file and the class field are compatible. 

Utilize Tools

Spring Boot provides a lot of feedback at startup time. Carefully read the error stack trace; it often gives specific details about the invalid property reference. You can also make use of the Spring Boot Actuator's /actuator/configprops endpoint to see a list of all the configuration properties and their bindings. 

In conclusion, the "invalid property reference" error in Spring Boot requires careful analysis of both your configuration properties and the way they are bound in your application. By methodically checking each possible cause, you can effectively pinpoint and address the root of the problem.