The magic number in GZip header is not correct. Ma

Question

I am trying to retrieve product name and its ids as NameID object from EntityFramework using WebAPI. code for which is as following.

public class ProductController : ApiController
{
    protected MainDataContext db = new MainDataContext();
    // GET /api/values
    public IQueryable<NameID> Get()
    {
        return db.Products.Select(x=>new NameID{ ID=x.ID,Name=x.Name }).AsQueryable();
    }

    // GET /api/values/5
    public NameID Get(long id)
    {
        var result = db.Products.Select(x=>new NameID{ ID=x.ID,Name=x.Name }).SingleOrDefault(x => x.ID == id);
        if (id == 0 || result == null)
            throw new HttpResponseException(HttpStatusCode.NotFound); 
        return result;
    }

}
public class NameID {
    public long ID {get;set;}
    public string Name {get;set;}
}

It throws error as following

The magic number in GZip header is not correct.
Make sure you are passing in a GZip stream.

at System.IO.Compression.GZipDecoder.ReadHeader(InputBuffer input) 
at System.IO.Compression.Inflater.Decode() 
at System.IO.Compression.Inflater.Inflate(Byte[] bytes, Int32 offset, Int32 length) 
at System.IO.Compression.DeflateStream.Read(Byte[] array, Int32 offset, Int32 count) 
at System.IO.Compression.GZipStream.Read(Byte[] array, Int32 offset, Int32 count) 
at System.Xml.XmlTextReaderImpl.InitStreamInput(Uri baseUri, String baseUriStr, Stream stream, Byte[] bytes, Int32 byteCount, Encoding encoding) 
at System.Xml.XmlTextReaderImpl..ctor(Stream stream, Byte[] bytes, Int32 byteCount, XmlReaderSettings settings, Uri baseUri, String baseUriStr, XmlParserContext context, Boolean closeInput) 
at System.Xml.XmlReaderSettings.CreateReader(Stream input, Uri baseUri, String baseUriString, XmlParserContext inputContext) 
at System.Xml.XmlReader.Create(Stream input, XmlReaderSettings settings, String baseUri) 
at System.Xml.Linq.XDocument.Load(Stream stream, LoadOptions options) 
at System.Data.Entity.Migrations.Edm.ModelCompressor.Decompress(Byte[] bytes) 
at System.Data.Entity.Migrations.History.HistoryRepository.GetLastModel(String& migrationId) 
at System.Data.Entity.Migrations.History.HistoryRepository.GetLastModel() 
at System.Data.Entity.Internal.InternalContext.QueryForModel() 
at System.Data.Entity.Internal.ModelCompatibilityChecker.CompatibleWithModel(InternalContext internalContext, ModelHashCalculator modelHashCalculator, Boolean throwIfNoMetadata) 
at System.Data.Entity.Internal.InternalContext.CompatibleWithModel(Boolean throwIfNoMetadata) 
at System.Data.Entity.CreateDatabaseIfNotExists`1.InitializeDatabase(TContext context) 
at System.Data.Entity.Internal.InternalContext.<>c__DisplayClass8.<PerformDatabaseInitialization>b__6() 
at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action) 
at System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization() 
at System.Data.Entity.Internal.LazyInternalContext.<InitializeDatabase>b__4(InternalContext c) 
at System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input) 
at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action) 
at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase() 
at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) 
at System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() 
at System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext() 
at System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider() 
at System.Linq.Queryable.Select[TSource,TResult](IQueryable`1 source, Expression`1 selector) 
at ProductAPI.Controllers.ProductController.Get() in D:\Demo\ProductAPI\Controllers\ProductController.cs:line 24 
at lambda_method(Closure , Object , Object[] ) 
at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments) 
at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.Execute(HttpControllerContext controllerContext, IDictionary`2 arguments) 
at System.Web.Http.Controllers.ApiControllerActionInvoker.<>c__DisplayClass2.<InvokeActionAsync>b__0() 
at System.Threading.Tasks.TaskHelpers.RunSynchronously[TResult](Func`1 func, CancellationToken cancellationToken)

Answer 1

The stack trace seems to indicate the there is a problem reading the Entity Framework model metadata from the database.

HistoryRepository.GetLastModel calls ModelCompressor.Decompress that uses XDocument.Load to read some XML from a GZipStream. This fails and the model metadata in the database is most likely corrupted.

You can try to recreate the database to get around this problem.

Answer 2

No way to recreate the database for me and I am already using Database.SetInitializer with null.

Fortunately, I have an up-to-date __MigrationHistory table on another database and I used this Sql query to set the correct value in the target database :

INSERT INTO TargetDbName.dbo.__MigrationHistory (MigrationId, Model, ProductVersion)
SELECT MigrationId, Model, ProductVersion
FROM SourceDbName.dbo.__MigrationHistory
WHERE MigrationId = 'YYYYMMDDHHMMSSFFF_LastMigration' 

Answer 3

Its a little late and there is already an accepted answer, which will work. But, if you already have a working database and do not want to refresh the database, then you can call Database.SetInitializer with null in Global.asax's application_start function. This will not looking for the __migrationhistory table that contains the corrupt data.