dotnet/efcore · error · InvalidOperationException

Property '{entityType}.{property}' was configured for full-t

Error message

Property '{entityType}.{property}' was configured for full-text search, but has type '{clrType}'; only string properties can be configured for full-text search.

What it means

Cosmos DB full-text search can only be applied to string properties. During container creation (CosmosClientWrapper.cs:248-255), EF Core iterates all properties marked with GetIsFullTextSearchEnabled() and throws if property.ClrType is not typeof(string). Non-string types (int, byte[], DateTime, etc.) are incompatible with the Cosmos full-text policy.

Source

Thrown at src/EFCore.Cosmos/Storage/Internal/CosmosClientWrapper.cs:250

                        ? CompositePathSortOrder.Descending
                        : CompositePathSortOrder.Ascending;
                    compositePaths.Add(new CompositePath { Path = path, Order = order });
                    key.Append(path).Append('=').Append(order).Append('|');
                }

                if (seenCompositeIndexes.Add(key.ToString()))
                {
                    compositeIndexes.Add(compositePaths);
                }
            }
        }

        var fullTextPaths = new Collection<FullTextPath>();
        foreach (var (property, language) in parameters.FullTextProperties)
        {
            if (property.ClrType != typeof(string))
            {
                throw new InvalidOperationException(
                    CosmosStrings.FullTextSearchConfiguredForUnsupportedPropertyType(
                        property.DeclaringType.DisplayName(),
                        property.Name,
                        property.ClrType.Name));
            }

            fullTextPaths.Add(
                new FullTextPath
                {
                    Path = GetJsonPropertyPathFromRoot(property),
                    // TODO: remove the fallback once Cosmos SDK allows optional language (see #35939)
                    Language = language ?? parameters.DefaultFullTextLanguage ?? "en-US"
                });
        }

        var embeddings = new Collection<Embedding>();
        foreach (var (property, vectorType) in parameters.Vectors)
        {

View on GitHub (pinned to dbf9771522)

Solutions

1. Only configure full-text search on string properties. Remove .IsFullTextSearch() from non-string properties.
2. If you need to search non-text data, store a string representation in a separate property and full-text index that.
3. Recreate the container after fixing the model.

Example fix

// before
modelBuilder.Entity<Document>()
    .Property(d => d.FileSize)  // int
    .IsFullTextSearch();

// after
modelBuilder.Entity<Document>()
    .Property(d => d.Content)   // string
    .IsFullTextSearch();

// Validate that every full-text-search-enabled property is a string.
foreach (var entityType in model.GetEntityTypes())
{
    foreach (var property in entityType.GetProperties())
    {
        if (property.GetIsFullTextSearchEnabled() == true && property.ClrType != typeof(string))
            throw new InvalidOperationException($"{property.Name} is full-text but not a string.");
    }
}

// Guard: only enable full-text search on string properties
static void ConfigureFullText<T>(EntityTypeBuilder<T> eb, Expression<Func<T, string>> prop)
    where T : class
    => eb.HasIndex(prop).ForCosmos().IsFullTextIndex();

When it happens

Trigger: Calling .IsFullTextSearch() (or configuring full-text search via the property API) on a non-string property, e.g. an int Id, a byte[] blob, or a DateTime. This fires at container-creation time when the full-text policy paths are built.

Common situations: Enabling full-text search on all indexed properties without checking their types. Applying a blanket convention that marks properties as full-text searchable. Migrating a schema where a numeric or binary field was previously searched.

Related errors

• The type '{givenType}' cannot be mapped as a dictionary beca
• The partition key value supplied for '{propertyType}' proper
• Ordering based on scoring function is not supported inside '
• Only one ordering using scoring function is allowed. Use 'EF
• Ordering using a scoring function is mutually exclusive with

AI-assisted analysis of dotnet/efcore@dbf9771522 (2026-08-06). Data as JSON: /api/errors/d4f50b014f9f6353. Report an issue: GitHub.