Hello, Im getting same exception and thus probably facing similar issue as described here:

https://github.com/spring-projects/spring-boot/issues/5669

The problem appears when I add logback-spring.xml to the project where simple console appender is defined using spring boot default pattern. This pattern works perfectly when it is configured/declared in application.yml so not expecting there is problem in it.

-%PARSER_ERROR[clr] %PARSER_ERROR[clr] %PARSER_ERROR[clr] %PARSER_ERROR[clr] %PARSER_ERROR[clr] %PARSER_ERROR[clr] %PARSER_ERROR[clr] %PARSER_ERROR[clr] Application run failed
-%PARSER_ERROR[wEx]java.lang.IllegalStateException: Logback configuration error detected: 
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - There is no conversion class registered for composite conversion word [clr]
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - Failed to create converter for [%clr] keyword
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - There is no conversion class registered for composite conversion word [clr]
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - Failed to create converter for [%clr] keyword
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - There is no conversion class registered for composite conversion word [clr]
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - Failed to create converter for [%clr] keyword
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - There is no conversion class registered for composite conversion word [clr]
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - Failed to create converter for [%clr] keyword
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - There is no conversion class registered for composite conversion word [clr]
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - Failed to create converter for [%clr] keyword
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - There is no conversion class registered for composite conversion word [clr]
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - Failed to create converter for [%clr] keyword
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - There is no conversion class registered for composite conversion word [clr]
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - Failed to create converter for [%clr] keyword
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - There is no conversion class registered for composite conversion word [clr]
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - Failed to create converter for [%clr] keyword
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - There is no conversion class registered for conversion word [wEx]
ERROR in ch.qos.logback.core.pattern.parser.Compiler@5fe94a96 - [wEx] is not a valid conversion word
    at org.springframework.boot.logging.logback.LogbackLoggingSystem.loadConfiguration(LogbackLoggingSystem.java:169)
    at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithConventions(AbstractLoggingSystem.java:80)
    at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:60)
    at org.springframework.boot.logging.logback.LogbackLoggingSystem.initialize(LogbackLoggingSystem.java:118)
    at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:313)
    at org.springframework.boot.context.logging.LoggingApplicationListener.initialize(LoggingApplicationListener.java:288)
    at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEnvironmentPreparedEvent(LoggingApplicationListener.java:246)
    at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:223)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127)
    at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:76)
    at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:53)
    at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:345)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:308)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    at logbackinitissue.demo.DemoApplication.main(DemoApplication.java:10)

logback-init-issue.zip

Comment From: wilkinsona

Support for clr and wEx is provided by Spring Boot but you have not included any of Spring Boot's default configuration in your logback-spring.xml. You can fix your problem by including Spring Boot's defaults.xml as recommended in the documentation. Your configuration would then look like this:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <include resource="org/springframework/boot/logging/logback/defaults.xml" />
    <springProperty scope="context" name="CONSOLE_PATTERN" source="application.console-pattern"/>
    <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>${CONSOLE_PATTERN}</pattern>
        </encoder>
    </appender>
    <root level="info">
        <appender-ref ref="consoleAppender" />
    </root>
</configuration>

Comment From: StepeCZ

Ooops, my mistake. Thank you very much.

Comment From: Mettbrot

I spent a couple of hours on this error because I copied the wring snippet from the docu https://docs.spring.io/spring-boot/docs/2.1.8.RELEASE/reference/html/howto-logging.html#howto-configure-logback-for-logging

In there it wrongly says defaulT.xml (without the s). Could you fix that please? https://github.com/spring-projects/spring-boot/issues/43244