LDAP connection keeps failing

I am using LDAP plugin to connect to the LDAP server (https://plugins.jenkins.io/ldap/).
When I want to test the connection, Iam I keep getting the fallowing message
“A problem occurred while processing the request.
Logging ID=06b1d7ed-5632-4ccc-9513-8868b1c05745”. Normally I should see an overview but this is not the case.

In Jenkins log I see the following:

Error while serving http://xxxxxxx:8080/descriptorByName/hudson.security.LDAPSecurityRealm/validate java.lang.NullPointerException at hudson.security.LDAPSecurityRealm$DescriptorImpl.validate(LDAPSecurityRealm.java:1589) at hudson.security.LDAPSecurityRealm$DescriptorImpl.validate(LDAPSecurityRealm.java:1589ity) $DescriptorImpl.doValidate(LDAPSecurityRealm.java:1544) at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:710) at org.kohsuke.stapler.Function$MethodFunction.invoke:(Function.javaction.java) ) Caused: java.lang.reflect.InvocationTargetException at org.kohsuke.stapler.Function$MethodFunction.invoke(Function.java:401) at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:409) at org .kohsuke.stapler.interceptor.RequirePOST$Processor.invoke(RequirePOST.java:78) at org.kohsuke.stapler.PreInvokeInterceptedFunction.invoke(PreInvokeInterceptedFunction.java:26) at org.kohsuke.bindlerAnd.Function. :207) at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java :140) at org.kohsuke.stapler.MetaClass$11.doDispatch(MetaClass.java:558) at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:59) at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.tryInvoke(Stapler .java:766) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:898).

Anyone any idea what I can do?
LDAP plugin version: 2.10
Jenkins version: 2.354
Mailer Plugin Version: 414.vcc4c33714601