de.siegmar.logbackgelf.GelfHttpAppender gives errors without message

[gbarsan]

We are using this settings:

<appender name="GELFNEW" class="de.siegmar.logbackgelf.GelfHttpAppender">
<uri>https://logs.example.com/gelf</uri>
<encoder class="de.siegmar.logbackgelf.GelfEncoder">
<staticField>application:${application}</staticField>
</encoder>
</appender>
<appender name="ASYNC_GELF" class="ch.qos.logback.classic.AsyncAppender">
<appender-ref ref="GELFNEW"/>
<queueSize>500</queueSize>
<neverBlock>true</neverBlock>
</appender>
<root level="DEBUG">
<appender-ref ref="ASYNC_GELF"/>
</root>

But it leads to this error on STDOUT:

12:08:02,466 |-ERROR in de.siegmar.logbackgelf.GelfHttpAppender[GELFNEW] - Invalid response from https://logs.example.com/gelf. Code: 413; Message:

Does anyone know how to handle this? How can we solve it?

Many thanks for any help!

[osiegmar]

HTTP error 413 resolves to "Content Too Large". Graylog (or the underlaying Elasticsearch) typically throws this error if the message is over ~32 KiB. Maybe that helps? What does the Graylog server log tell you?

[gbarsan]

We're trying to figure out how to find the according entries and see what Graylog "says". At least on NGINX (which we use as reverse proxy/for SSL termination) we don't see any errors. We will also try to implement a custom message filter and limit the size.