Unable to determine the serialization information for "Expression" - mongodb

Question

I receive the error message Unable to determine the serialization information for a => a.CurrentProcessingStep when I try to Update my document.
I'm using the Mongo .NET Driver version 2.8 and .NET Framework 4.7.2.
I'm building the filter and update statements using the builder helpers from the library.
Here is the relevant section of my document class:
[BsonIgnoreExtraElements]
[DebuggerDisplay("{Term}, Rule Status = {_ruleStatus}, Current Step = {_currentProcessingStep}")]
public class SearchTermInfo : AMongoConnectedObject
{
[BsonElement("CurrentProcessingStep")]
private ProcessingStep _currentProcessingStep;
[BsonElement("RuleStatus")]
private RuleStatus _ruleStatus;
[BsonDateTimeOptions(Kind = DateTimeKind.Local)]
public DateTime AddDateTime { get; set; }
[BsonIgnore]
[JsonIgnore]
public ProcessingStep CurrentProcessingStep
{
get => _currentProcessingStep;
set => AddHistoryRecord(value);
}
[BsonIgnore]
[JsonIgnore]
public RuleStatus RuleStatus
{
get => _ruleStatus;
set => AddHistoryRecord(value);
}
I'm building the filter with this code:
FilterDefinition<SearchTermInfo> filter = Builders<SearchTermInfo>.Filter.And(
Builders<SearchTermInfo>.Filter.Eq(a => a.Id, recordId),
Builders<SearchTermInfo>.Filter.Or(
Builders<SearchTermInfo>.Filter.Eq(a => a.CurrentProcessingStep, currentStep),
Builders<SearchTermInfo>.Filter.Exists("CurrentProcessingStep", false)
)
);
Then I execute the update:
UpdateResult results =
searchTermInfoCollection.MongoCollection.UpdateOne(filter, update, null, cancellationToken);
and I get this error:
? ex
{"Unable to determine the serialization information for a => a.CurrentProcessingStep."}
Data: {System.Collections.ListDictionaryInternal}
HResult: -2146233079
HelpLink: null
InnerException: null
Message: "Unable to determine the serialization information for a => a.CurrentProcessingStep."
Source: "MongoDB.Driver"
StackTrace: " at MongoDB.Driver.ExpressionFieldDefinition`2.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry, Boolean allowScalarValueForArrayField)
at MongoDB.Driver.SimpleFilterDefinition`2.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry)\r\n
at MongoDB.Driver.OrFilterDefinition`1.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry)\r\n
at MongoDB.Driver.AndFilterDefinition`1.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry)\r\n
at MongoDB.Driver.MongoCollectionImpl`1.ConvertWriteModelToWriteRequest(WriteModel`1 model, Int32 index)\r\n
at System.Linq.Enumerable.<SelectIterator>d__5`2.MoveNext()\r\n
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)\r\n
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)\r\n
at MongoDB.Driver.Core.Operations.BulkMixedWriteOperation..ctor(CollectionNamespace collectionNamespace, IEnumerable`1 requests, MessageEncoderSettings messageEncoderSettings)\r\n
at MongoDB.Driver.MongoCollectionImpl`1.CreateBulkWriteOperation(IEnumerable`1 requests, BulkWriteOptions options)\r\n
at MongoDB.Driver.MongoCollectionImpl`1.BulkWrite(IClientSessionHandle session, IEnumerable`1 requests, BulkWriteOptions options, CancellationToken cancellationToken)\r\n
at MongoDB.Driver.MongoCollectionImpl`1.<>c__DisplayClass23_0.<BulkWrite>b__0(IClientSessionHandle session)\r\n
at MongoDB.Driver.MongoCollectionImpl`1.UsingImplicitSession[TResult](Func`2 func, CancellationToken cancellationToken)\r\n
at MongoDB.Driver.MongoCollectionImpl`1.BulkWrite(IEnumerable`1 requests, BulkWriteOptions options, CancellationToken cancellationToken)\r\n
at MongoDB.Driver.MongoCollectionBase`1.UpdateOne(FilterDefinition`1 filter, UpdateDefinition`1 update, UpdateOptions options, Func`3 bulkWrite)\r\n
at MongoDB.Driver.MongoCollectionBase`1.UpdateOne(FilterDefinition`1 filter, UpdateDefinition`1 update, UpdateOptions options, CancellationToken cancellationToken)\r\n
at SaFileIngestion.FileProcessorEngine.LockRecord(Int64 recordId, ProcessingStep currentStep, CancellationToken cancellationToken)
in D:\\[File Path]\\SaFileIngestion\\FileProcessorEngine.cs:line 195"
TargetSite: {MongoDB.Driver.RenderedFieldDefinition`1[TField] Render(MongoDB.Bson.Serialization.IBsonSerializer`1[TDocument], MongoDB.Bson.Serialization.IBsonSerializerRegistry, Boolean)}
I've also tried to build the filter with this code:
Builders<SearchTermInfo>.Filter.Eq("CurrentProcessingStep", currentStep),
It was my impression that I should be able to build an expression using the property accessor, even though it is flagged as BsonIgnore, since the private field has been attributed with BsonElementAttribute with the same name as the ignored property accessor.
Any guidance provided is appreciated.
Thanks

Answer 1

I eventually resolved this. I don't remember the exact solution as it was over a year ago. I do remember there was something wrong with the way the query was being constructed.