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This page documents API and behavior changes that have the potential to break existing applications updating from EF Core 10 to EF Core 11. Make sure to review earlier breaking changes if updating from an earlier version of EF Core:
Summary
| Breaking change | Impact |
|---|---|
| Sync I/O via the Azure Cosmos DB provider has been fully removed | Medium |
Medium-impact changes
Sync I/O via the Azure Cosmos DB provider has been fully removed
Old behavior
Synchronous I/O via the Azure Cosmos DB provider has been unsupported since EF 9.0 (note); calling any sync I/O API - like ToList or SaveChanges threw an exception, unless a special opt-in was configured. When the opt-in was configured, sync I/O APIs worked as before, causing the provider to perform "sync-over-async" blocking against the Azure Cosmos DB SDK, which could result in deadlocks and other performance issues.
New behavior
Starting with EF Core 11.0, EF now always throws when a synchronous I/O API is called. There is no way to opt back into using sync I/O APIs.
Why
Synchronous blocking on asynchronous methods ("sync-over-async") is highly discouraged, and can lead to deadlock and other performance problems. Since the Azure Cosmos DB SDK only supports async methods, so does the EF Cosmos provider.
Mitigations
Convert your code to use async I/O APIs instead of sync I/O ones. For example, replace calls to SaveChanges() with await SaveChangesAsync().
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