I set up a connection using the visual interface.
The connection is set to sync automatically in one direction only: from server to cloud
We are syncing Issues only. We have successfully synced a number of issues under different projects.
In this case, For each field option: "If no matching value" I selected "Report an error"

I set up a Trigger to select issues for a certain project created between specific dates. 
I tried the bulk Exalate option.
On the receiving side I saw the connection appear, with an error: see below

It's not clear to me when it objects to 'null' which field or how to identify the specific cause. 
It's noting that the error type is connection configuration, so I'm thinking I need to specify a value somewhere but it's not clear to me how to identify which value I need to specify. 

Is this maybe a limitation of the GUI; would it be better to switch to scripting? 

I can't see what the next step is in the troubleshooting process.

Thanks for any feedback

---------------------------------
Impact:
Sync for remote issue SNIP is blocked
Remote issue:
SNIP
Connection:
Jira_Server_SNIP_to_Jira_Cloud_SNIP
Error Type:
Connection configuration
Error Creation Time:
Mar 24, 2022 01:08:31
Error Detail Message:
Missing mapping. Please add mapping for `null`.Check the documentation for more details.
Error Stack Trace
com.exalate.domain.exception.editor.RecoveryMappingEditorException: com.exalate.admin.editor.errors.mappings.recovery at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490) at org.codehaus.groovy.reflection.CachedConstructor.invoke(CachedConstructor.java:80) at org.codehaus.groovy.runtime.callsite.ConstructorSite$ConstructorSiteNoUnwrapNoCoerce.callConstructor(ConstructorSite.java:105) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallConstructor(CallSiteArray.java:59) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callConstructor(AbstractCallSite.java:237) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callConstructor(AbstractCallSite.java:273) at Script29$_run_closure1$_closure5.doCall(Script29.groovy:3) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101) at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323) at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:263) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1041) at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:37) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:127) at Script29$_run_closure1.doCall(Script29.groovy:18) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101) at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323) at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:263) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1041) at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:37) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:151) at Script29$_run_closure2.doCall(Script29.groovy:27) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101) at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323) at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:263) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1041) at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:37) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115) at Script29$_run_closure4.doCall(Script29.groovy:129) at Script29$_run_closure4.doCall(Script29.groovy) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101) at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323) at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:263) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1041) at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:37) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:119) at Script29.run(Script29.groovy:82) at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.eval(GroovyScriptEngineImpl.java:317) at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.eval(GroovyScriptEngineImpl.java:155) at java.scripting/javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:264) at com.exalate.processor.ExalateProcessor.execute(ExalateProcessor.java:98) at com.exalate.processor.ExalateProcessor.executeProcessor(ExalateProcessor.java:55) at com.exalate.replication.services.replication.mapping.MappingService.$anonfun$executeInScriptRule$1(MappingService.scala:272) at scala.util.Try$.apply(Try.scala:213) at com.exalate.replication.services.replication.mapping.MappingService.executeInScriptRule(MappingService.scala:269) at com.exalate.replication.services.replication.mapping.MappingService.$anonfun$receive$8(MappingService.scala:181) at scala.concurrent.Future.$anonfun$flatMap$1(Future.scala:307) at scala.concurrent.impl.Promise.$anonfun$transformWith$1(Promise.scala:41) at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:64) at akka.dispatch.BatchingExecutor$AbstractBatch.processBatch(BatchingExecutor.scala:56) at akka.dispatch.BatchingExecutor$BlockableBatch.$anonfun$run$1(BatchingExecutor.scala:93) at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23) at scala.concurrent.BlockContext$.withBlockContext(BlockContext.scala:85) at akka.dispatch.BatchingExecutor$BlockableBatch.run(BatchingExecutor.scala:93) at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:48) at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(ForkJoinExecutorConfigurator.scala:48) at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290) at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020) at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656) at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594) at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)