`Bitbucket Notifier` has a dependency on the `[Jenkins Multiple SCMs|https://plugins.jenkins.io/multiple-scms/]` which currently deprecated and has not been updated for ~4 years.  

When scanning repos to add a new repo, we get a stack trace:
java.lang.NullPointerException: Descriptor list is null for context 'class hudson.model.Hudson' in thread 'Handling GET /configure from 174.65.113.32 : Jetty (winstone)-223488 Jenkins/configure.jelly GlobalLibraries/config.jelly LibraryConfiguration/config.jelly SCMRetriever/DescriptorImpl/config.jelly MultiSCM/DescriptorImpl/config.jelly'
at hudson.model.DescriptorVisibilityFilter.apply(DescriptorVisibilityFilter.java:73)
at hudson.Functions.filterDescriptors(Functions.java:2045)
at sun.reflect.GeneratedMethodAccessor836.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.commons.jexl.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:258)
at org.apache.commons.jexl.parser.ASTMethod.execute(ASTMethod.java:104)
at org.apache.commons.jexl.parser.ASTReference.execute(ASTReference.java:83)
at org.apache.commons.jexl.parser.ASTReference.value(ASTReference.java:57)
at org.apache.commons.jexl.parser.ASTReferenceExpression.value(ASTReferenceExpression.java:51)
at org.apache.commons.jexl.ExpressionImpl.evaluate(ExpressionImpl.java:80)
at hudson.ExpressionFactory2$JexlExpression.evaluate(ExpressionFactory2.java:74)
at org.apache.commons.jelly.tags.core.CoreTagLibrary$3.run(CoreTagLibrary.java:134)
 

This is very similar to this issue:

https://issues.jenkins-ci.org/browse/JENKINS-52837

which was resolved by moving away from the Jenkins Multiple SCM plugin.