here is complete log from app builded using `mcr.microsoft.com/dotnet/core/aspnet:2.2-stretch-slim`. So, seems that this issue doen't depend of linux distib:
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Infrastructure[10401]
An 'IServiceProvider' was created for internal use by Entity Framework.
[40m[32minfo[39m[22m[49m: Microsoft.EntityFrameworkCore.Infrastructure[10403]
Entity Framework Core 2.2.1-servicing-10028 initialized 'MyDbContext' using provider 'Devart.Data.Oracle.Entity.EFCore' with options: MigrationsAssembly=PUR.DataAccess
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Migrations[20400]
Migrating using database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20000]
Opening connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20001]
Opened connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Command[20100]
Executing DbCommand [Parameters=[], CommandType='Text', CommandTimeout='600']
SELECT COUNT(*)
FROM SYS.ALL_TABLES
WHERE (OWNER = SYS_CONTEXT('USERENV', 'CURRENT_SCHEMA') AND TABLE_NAME = 'EFMIGRATIONSHISTORY__')
[40m[32minfo[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Command[20101]
Executed DbCommand (106ms) [Parameters=[], CommandType='Text', CommandTimeout='600']
SELECT COUNT(*)
FROM SYS.ALL_TABLES
WHERE (OWNER = SYS_CONTEXT('USERENV', 'CURRENT_SCHEMA') AND TABLE_NAME = 'EFMIGRATIONSHISTORY__')
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20002]
Closing connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20003]
Closed connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20000]
Opening connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20001]
Opened connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Command[20100]
Executing DbCommand [Parameters=[], CommandType='Text', CommandTimeout='600']
SELECT COUNT(*)
FROM SYS.ALL_TABLES
WHERE (OWNER = SYS_CONTEXT('USERENV', 'CURRENT_SCHEMA') AND TABLE_NAME = 'EFMIGRATIONSHISTORY__')
[40m[32minfo[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Command[20101]
Executed DbCommand (2ms) [Parameters=[], CommandType='Text', CommandTimeout='600']
SELECT COUNT(*)
FROM SYS.ALL_TABLES
WHERE (OWNER = SYS_CONTEXT('USERENV', 'CURRENT_SCHEMA') AND TABLE_NAME = 'EFMIGRATIONSHISTORY__')
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20002]
Closing connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20003]
Closed connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20000]
Opening connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20001]
Opened connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Command[20100]
Executing DbCommand [Parameters=[], CommandType='Text', CommandTimeout='600']
SELECT MigrationId, ProductVersion
FROM EFMigrationsHistory__
ORDER BY MigrationId
[40m[32minfo[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Command[20101]
Executed DbCommand (5ms) [Parameters=[], CommandType='Text', CommandTimeout='600']
SELECT MigrationId, ProductVersion
FROM EFMigrationsHistory__
ORDER BY MigrationId
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Command[20300]
A data reader was disposed.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20002]
Closing connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Database.Connection[20003]
Closed connection to database '' on server '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.10.10.10)(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=test)))'.
[40m[32minfo[39m[22m[49m: Microsoft.EntityFrameworkCore.Migrations[20402]
Applying migration '20190806103120_VarcharToNvarchar'.
[40m[37mdbug[39m[22m[49m: Microsoft.EntityFrameworkCore.Infrastructure[10407]
'MyDbContext' disposed.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Hosting.Internal.WebHost[3]
Hosting starting
[40m[32minfo[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[0]
User profile is available. Using '/root/.aspnet/DataProtection-Keys' as key repository; keys will not be encrypted at rest.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.DefaultKeyResolver[53]
Repository contains no viable default key. Caller should generate a key with immediate activation.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingProvider[57]
Policy resolution states that a new key should be added to the key ring.
[40m[32minfo[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[58]
Creating key {cd0d7ea2-143b-4f4d-8e11-52d252d0a23b} with creation date 2019-08-30 05:25:49Z, activation date 2019-08-30 05:25:49Z, and expiration date 2019-11-28 05:25:49Z.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[32]
Descriptor deserializer type for key {cd0d7ea2-143b-4f4d-8e11-52d252d0a23b} is 'Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ConfigurationModel.AuthenticatedEncryptorDescriptorDeserializer, Microsoft.AspNetCore.DataProtection, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[34]
No key escrow sink found. Not writing key {cd0d7ea2-143b-4f4d-8e11-52d252d0a23b} to escrow.
[40m[1m[33mwarn[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[35]
No XML encryptor configured. Key {cd0d7ea2-143b-4f4d-8e11-52d252d0a23b} may be persisted to storage in unencrypted form.
[40m[32minfo[39m[22m[49m: Microsoft.AspNetCore.DataProtection.Repositories.FileSystemXmlRepository[39]
Writing data to file '/root/.aspnet/DataProtection-Keys/key-cd0d7ea2-143b-4f4d-8e11-52d252d0a23b.xml'.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[23]
Key cache expiration token triggered by 'CreateNewKey' operation.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.Repositories.FileSystemXmlRepository[37]
Reading data from file '/root/.aspnet/DataProtection-Keys/key-cd0d7ea2-143b-4f4d-8e11-52d252d0a23b.xml'.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[18]
Found key {cd0d7ea2-143b-4f4d-8e11-52d252d0a23b}.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.DefaultKeyResolver[13]
Considering key {cd0d7ea2-143b-4f4d-8e11-52d252d0a23b} with expiration date 2019-11-28 05:25:49Z as default key.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.TypeForwardingActivator[0]
Forwarded activator type request from Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ConfigurationModel.AuthenticatedEncryptorDescriptorDeserializer, Microsoft.AspNetCore.DataProtection, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60 to Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ConfigurationModel.AuthenticatedEncryptorDescriptorDeserializer, Microsoft.AspNetCore.DataProtection, Culture=neutral, PublicKeyToken=adb9793829ddae60
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ManagedAuthenticatedEncryptorFactory[11]
Using managed symmetric algorithm 'System.Security.Cryptography.Aes'.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ManagedAuthenticatedEncryptorFactory[10]
Using managed keyed hash algorithm 'System.Security.Cryptography.HMACSHA256'.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingProvider[2]
Using key {cd0d7ea2-143b-4f4d-8e11-52d252d0a23b} as the default key.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.DataProtection.Internal.DataProtectionStartupFilter[0]
Key ring with default key {cd0d7ea2-143b-4f4d-8e11-52d252d0a23b} was loaded during application startup.
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcJsonOptions[0]
Compatibility switch AllowInputFormatterExceptionMessages in type MvcJsonOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcOptions[0]
Compatibility switch AllowCombiningAuthorizeFilters in type MvcOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcOptions[0]
Compatibility switch AllowBindingHeaderValuesToNonStringModelTypes in type MvcOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcOptions[0]
Compatibility switch AllowValidatingTopLevelNodes in type MvcOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcOptions[0]
Compatibility switch InputFormatterExceptionPolicy in type MvcOptions is using compatibility value MalformedInputExceptions for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcOptions[0]
Compatibility switch SuppressBindingUndefinedValueToEnumType in type MvcOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcOptions[0]
Compatibility switch EnableEndpointRouting in type MvcOptions is using default value False
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcOptions[0]
Compatibility switch MaxValidationDepth in type MvcOptions is using default value (null)
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcOptions[0]
Compatibility switch AllowShortCircuitingValidationWhenNoValidatorsArePresent in type MvcOptions is using default value False
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.ApiBehaviorOptions[0]
Compatibility switch SuppressMapClientErrors in type ApiBehaviorOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.ApiBehaviorOptions[0]
Compatibility switch SuppressUseValidationProblemDetailsForInvalidModelStateResponses in type ApiBehaviorOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.ApiBehaviorOptions[0]
Compatibility switch AllowInferringBindingSourceForCollectionTypesAsFromQuery in type ApiBehaviorOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.RazorPages.RazorPagesOptions[0]
Compatibility switch AllowAreas in type RazorPagesOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.RazorPages.RazorPagesOptions[0]
Compatibility switch AllowMappingHeadRequestsToGetHandler in type RazorPagesOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.RazorPages.RazorPagesOptions[0]
Compatibility switch AllowDefaultHandlingForOptionsRequests in type RazorPagesOptions is using default value False
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.Razor.RazorViewEngineOptions[0]
Compatibility switch AllowRecompilingViewsOnFileChange in type RazorViewEngineOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcViewOptions[0]
Compatibility switch SuppressTempDataAttributePrefix in type MvcViewOptions is using compatibility value True for version Version_2_1
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.MvcViewOptions[0]
Compatibility switch AllowRenderingMaxLengthAttribute in type MvcViewOptions is using default value False
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Mvc.ModelBinding.ModelBinderFactory[12]
Registered model binder providers, in the following order: Microsoft.AspNetCore.Mvc.ModelBinding.Binders.BinderTypeModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ServicesModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.BodyModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.HeaderModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.FloatingPointTypeModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.EnumTypeModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.SimpleTypeModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.CancellationTokenModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ByteArrayModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.FormFileModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.FormCollectionModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.KeyValuePairModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.DictionaryModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ArrayModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.CollectionModelBinderProvider, Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ComplexTypeModelBinderProvider
[40m[37mdbug[39m[22m[49m: Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer[2]
Failed to locate the development https certificate at '(null)'.
Hosting environment: Test
Content root path: /app
Now listening on: http://[::]:5000
Application started. Press Ctrl+C to shut down.
as you can see, after `Applying migration '20190806103120_VarcharToNvarchar'.` nothing happen expect context disposing.
FYI, `Applying migration '20190806103120_VarcharToNvarchar'` it's not last migration. There is few more after it.