Invalid character found in the request target

We are getting this error frequently when using our flowable engine.
Anyone know how to solve this and why does this happen?

2023-03-21 12:47:48.146  INFO 1 --- [nio-8080-exec-5] o.apache.coyote.http11.Http11Processor   : Error parsing HTTP request header
 Note: further occurrences of HTTP request parsing errors will be logged at DEBUG level.
java.lang.IllegalArgumentException: Invalid character found in the request target [/flowable-rest/#/ ]. The valid characters are defined in RFC 7230 and RFC 3986
	at org.apache.coyote.http11.Http11InputBuffer.parseRequestLine(Http11InputBuffer.java:502) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:269) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1732) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at java.base/java.lang.Thread.run(Unknown Source) ~[na:na]

Hey @gcamaralooplex,
Can you send the http header you try to send? There seems to be some invalid char.

Greetings

Christopher