dotnet/efcore · error · InvalidOperationException

The partition key properties for entity type '{entityType1}'

Error message

The partition key properties for entity type '{entityType1}' are '{props1}', while the partition key properties for entity type '{entityType2}' are '{props2}', and both entity types are mapped to the container '{containerName}'. All entity types mapped to the same container must have compatible partition keys defined.

What it means

All entity types sharing a Cosmos container must have compatible partition keys (same number of partition key properties). CosmosModelValidator throws InvalidOperationException via CosmosStrings.NoPartitionKey when the partition key property-name counts differ between two types in the same container, since Cosmos uses a single physical partition key path per container.

Source

Thrown at src/EFCore.Cosmos/Infrastructure/Internal/CosmosModelValidator.cs:166

        foreach (var entityType in mappedTypes)
        {
            Check.DebugAssert(entityType.IsDocumentRoot(), "Only document roots expected here.");

            var storeNames = entityType.GetPartitionKeyPropertyNames()
                .Select(n => entityType.FindProperty(n)?.GetJsonPropertyName())
                .ToList();

            if (firstEntityType is null)
            {
                partitionKeyStoreNames = storeNames;
                firstEntityType = entityType;
            }
            else
            {
                if (partitionKeyStoreNames.Count != storeNames.Count)
                {
                    throw new InvalidOperationException(
                        CosmosStrings.NoPartitionKey(
                            firstEntityType.DisplayName(),
                            string.Join(",", partitionKeyStoreNames),
                            entityType.DisplayName(),
                            string.Join(",", storeNames),
                            container));
                }

                for (var i = 0; i < storeNames.Count; i++)
                {
                    if (!string.Equals(storeNames[i], partitionKeyStoreNames[i], StringComparison.Ordinal))
                    {
                        throw new InvalidOperationException(
                            CosmosStrings.PartitionKeyStoreNameMismatch(
                                firstEntityType.GetPartitionKeyPropertyNames()[i],
                                firstEntityType.DisplayName(),
                                partitionKeyStoreNames[i],
                                entityType.GetPartitionKeyPropertyNames()[i],

View on GitHub (pinned to dbf9771522)

Solutions

  1. Give every entity type mapped to the shared container the same partition key property set (same count and compatible names).
  2. If a type needs a different partition key strategy, map it to a different container.
  3. Centralize partition-key configuration in a shared convention so all roots in a container agree.

Example fix

// before (mismatched partition key counts in one container)
modelBuilder.Entity<Order>().ToContainer("docs").HasPartitionKey(o => o.TenantId);
modelBuilder.Entity<Invoice>().ToContainer("docs").HasPartitionKey(i => i.Region).HasPartitionKey(i => i.CustomerId);

// after (both use the same single partition key)
modelBuilder.Entity<Order>().ToContainer("docs").HasPartitionKey(o => o.TenantId);
modelBuilder.Entity<Invoice>().ToContainer("docs").HasPartitionKey(i => i.TenantId);
Defensive patterns

Strategy: validation

Validate before calling

// All roots in one container must have the same partition key property count.
var byContainer = modelBuilder.Model.GetEntityTypes()
    .Where(e => e.FindPrimaryKey() != null && e.GetContainer() != null)
    .GroupBy(e => e.GetContainer());
foreach (var g in byContainer)
{
    var counts = g.Select(e => e.GetPartitionKeyPropertyNames().Count).Distinct();
    if (counts.Count() > 1)
        throw new InvalidOperationException($"Container {g.Key} has mismatched partition key counts.");
}

Try / catch

try { context.Database.EnsureCreated(); }
catch (InvalidOperationException ex) when (ex.Message.Contains("compatible partition keys"))
{ throw new InvalidOperationException("Align partition key property sets across types in the shared container.", ex); }

Prevention

When it happens

Trigger: Two entity types mapped to the same container where one has HasPartitionKey configured (1+ properties) and the other has none, or they specify different numbers of partition key properties (e.g. single-key vs hierarchical).

Common situations: Sharing a container across multiple roots and forgetting to set partition keys on all of them; mixing single and hierarchical partition keys in one container; copy-paste of entity configs into a shared container.

Related errors

AI-assisted analysis of dotnet/efcore@dbf9771522 (2026-08-06). Data as JSON: /api/errors/bc76b2d9ded00a7e. Report an issue: GitHub.