litedb-org/LiteDB · error · InvalidOperationException

Cannot access non-array type value on {this.RawValue}

Error message

Cannot access non-array type value on {this.RawValue}

What it means

Thrown by the virtual int-indexer on the base BsonValue class when an element access (value[index]) is attempted on a BsonValue that is not a BsonArray. Only BsonArray overrides this indexer; all other types inherit the throwing base implementation. The message includes the current RawValue for diagnostics.

Source

Thrown at LiteDB/Document/BsonValue.cs:212

        #endregion

        #region Index "this" property

        /// <summary>
        /// Get/Set a field for document. Fields are case sensitive - Works only when value are document
        /// </summary>
        public virtual BsonValue this[string name]
        {
            get => throw new InvalidOperationException("Cannot access non-document type value on " + this.RawValue);
            set => throw new InvalidOperationException("Cannot access non-document type value on " + this.RawValue);
        }

        /// <summary>
        /// Get/Set value in array position. Works only when value are array
        /// </summary>
        public virtual BsonValue this[int index]
        {
            get => throw new InvalidOperationException("Cannot access non-array type value on " + this.RawValue);
            set => throw new InvalidOperationException("Cannot access non-array type value on " + this.RawValue);
        }

        #endregion

        #region Convert types

        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
        public BsonArray AsArray => this as BsonArray;

        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
        public BsonDocument AsDocument => this as BsonDocument;

        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
        public Byte[] AsBinary => this.RawValue as Byte[];

        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
        public bool AsBoolean => (bool)this.RawValue;

View on GitHub (pinned to f906a5f850)

Solutions

1. Check `value.IsArray` (or `value.AsArray != null`) before indexing.
2. Use `value.AsArray` with a null-check and default to an empty result.
3. Normalize the stored data so the field is consistently an array.

Example fix

// before
var first = items[0];
// after
var first = items.IsArray && items.AsArray.Count > 0 ? items[0] : BsonValue.Null;

if (!value.IsArray) throw new InvalidOperationException($"Expected array, got {value.Type}");
var item = value[0];

static bool IsBsonArray(BsonValue v) => v != null && v.IsArray;

When it happens

Trigger: Accessing `someBsonValue[0]` or `value[i]` where the value is a document, string, number, null, or any non-array type. Treating a scalar result as a list and indexing into it.

Common situations: A query field that was expected to be an array is stored as a single scalar or document. Reading a field that is sometimes null. Mixed data where some documents have arrays and others have scalars for the same field.

Related errors

• Cannot access non-document type value on {this.RawValue}
• The current collection implementation does not support vecto
• Value cannot be null. (Parameter 'doc')
• Value cannot be null. (Parameter 'buffer')
• Value cannot be null. (Parameter 'array')

AI-assisted analysis of litedb-org/LiteDB@f906a5f850 (2026-08-13). Data as JSON: /api/errors/60e7caec96ff26e3. Report an issue: GitHub.