If you post data to Solr, you can get an error like this:
org.apache.solr.update.processor.AddSchemaFieldsUpdateProcessorFactory$AddSchemaFieldsUpdateProcessor.mapValueClassesToFieldType(AddSchemaFieldsUpdateProcessorFactory.java:369) at org.apache.solr.update.processor.AddSchemaFieldsUpdateProcessorFactory$AddSchemaFieldsUpdateProcessor.processAdd(AddSchemaFieldsUpdateProcessorFactory.java:287) at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:48) at org.apache.solr.update.processor.FieldMutatingUpdateProcessor.processAdd(FieldMutatingUpdateProcessor.java:117) at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:48) at org.apache.solr.update.processor.FieldMutatingUpdateProcessor.processAdd(FieldMutatingUpdateProcessor.java:117) at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:48) at org.apache.solr.update.processor.FieldMutatingUpdateProcessor.processAdd(FieldMutatingUpdateProcessor.java:117) at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:48) at org.apache.solr.update.processor.FieldMutatingUpdateProcessor.processAdd(FieldMutatingUpdateProcessor.java:117) at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:48) at org.apache.solr.update.processor.FieldNameMutatingUpdateProcessorFactory$1.processAdd(FieldNameMutatingUpdateProcessorFactory.java:74) at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:48) at org.apache.solr.update.processor.FieldMutatingUpdateProcessor.processAdd(FieldMutatingUpdateProcessor.java:117) at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:48) at org.apache.solr.update.processor.DistributedUpdateProcessor.doLocalAdd(DistributedUpdateProcessor.java:931) at org.apache.solr.update.processor.DistributedUpdateProcessor.versionAdd(DistributedUpdateProcessor.java:1086) at org.apache.solr.update.processor.DistributedUpdateProcessor.processAdd(DistributedUpdateProcessor.java:709) at org.apache.solr.update.processor.LogUpdateProcessorFactory$LogUpdateProcessor.processAdd(LogUpdateProcessorFactory.java:103) at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:48) at org.apache.solr.update.processor.AbstractDefaultValueUpdateProcessorFactory$DefaultValueUpdateProcessor.processAdd(AbstractDefaultValueUpdateProcessorFactory.java:93) at org.apache.solr.handler.loader.JsonLoader$SingleThreadedJsonLoader.processUpdate(JsonLoader.java:143) at org.apache.solr.handler.loader.JsonLoader$SingleThreadedJsonLoader.load(JsonLoader.java:113) at org.apache.solr.handler.loader.JsonLoader.load(JsonLoader.java:76)
If you look at the source to this, this code is trying to loop over the array values of a field, and it’s values are null.
Interestingly, the provided update utility can handle nulls in the data (perhaps it cleans it out?), but if you post yourself, Solr will give up. The solution is to find and remove the null values in your data. If you’re using field suffixes to show Solr the type of data, you should also make sure these are correct.