我在使用Postgresql数据库时也遇到了同样的问题。为了管理迁移，我使用EF。在尝试向应用程序添加迁移时，我遇到了这个奇怪的问题。在我开始使用SQL Server之前，我从未遇到过这个问题。

System.Security.Cryptography.CryptographicException: An error occurred while trying to encrypt the provided data. Refer to the inner exception for more information.
     ---> Npgsql.PostgresException (0x80004005): 42P01: relation "DataProtectionKey" does not exist
       at Npgsql.NpgsqlConnector.<>c__DisplayClass160_0.<<DoReadMessage>g__ReadMessageLong|0>d.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at Npgsql.NpgsqlConnector.<>c__DisplayClass160_0.<<DoReadMessage>g__ReadMessageLong|0>d.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at Npgsql.NpgsqlDataReader.NextResult(Boolean async, Boolean isConsuming)
       at Npgsql.NpgsqlDataReader.NextResult()
       at Npgsql.NpgsqlCommand.ExecuteReaderAsync(CommandBehavior behavior, Boolean async, CancellationToken cancellationToken)
       at Npgsql.NpgsqlCommand.ExecuteReader(CommandBehavior behavior)
       at Npgsql.NpgsqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
       at System.Data.Common.DbCommand.ExecuteReader()
       at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReader(RelationalCommandParameterObject parameterObject)
       at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.InitializeReader(DbContext _, Boolean result)
       at Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.NpgsqlExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
       at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.MoveNext()
       at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at Microsoft.AspNetCore.DataProtection.EntityFrameworkCore.EntityFrameworkCoreXmlRepository`1.GetAllElements()
       at Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager.GetAllKeys()
       at Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingProvider.CreateCacheableKeyRingCore(DateTimeOffset now, IKey keyJustAdded)
       at Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingProvider.Microsoft.AspNetCore.DataProtection.KeyManagement.Internal.ICacheableKeyRingProvider.GetCacheableKeyRing(DateTimeOffset now)
       at Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingProvider.GetCurrentKeyRingCore(DateTime utcNow, Boolean forceRefresh)
       at Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingProvider.GetCurrentKeyRing()
       at Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingBasedDataProtector.Protect(Byte[] plaintext)
      Exception data:
        Severity: ERROR
        SqlState: 42P01
        MessageText: relation "DataProtectionKey" does not exist
        Position: 22
        File: parse_relation.c
        Line: 1381
        Routine: parserOpenTable
       --- End of inner exception stack trace ---
       at Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingBasedDataProtector.Protect(Byte[] plaintext)
       at Microsoft.AspNetCore.DataProtection.DataProtectionCommonExtensions.Protect(IDataProtector protector, String plaintext)
       at Microsoft.EntityFrameworkCore.Storage.ValueConversion.ValueConverter`2.<>c__DisplayClass3_0`2.<SanitizeConverter>b__0(Object v)
       at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetValue(ColumnModification columnModification)
       at System.Linq.Enumerable.WhereSelectListIterator`2.ToList()
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDataOperations(DiffContext diffContext)+MoveNext()
       at System.Linq.Enumerable.ConcatIterator`1.MoveNext()
       at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Sort(IEnumerable`1 operations, DiffContext diffContext)
       at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDifferences(IModel source, IModel target)
       at Microsoft.EntityFrameworkCore.Migrations.Design.MigrationsScaffolder.ScaffoldMigration(String migrationName, String rootNamespace, String subNamespace, String language)
       at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType)
       at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType)
       at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
       at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
       at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)

我正在使用：
1..NET核心3.1
1.执行文件3.1.13
1..数据保护.实体框架3.1.13
1.数据库管理系统
我应用程序数据库上下文具有此定义

....
 public DbSet<DataProtectionKey> DataProtectionKeys { get; set; }
 public DbSet<DataAudit> AuditTrail { get; set; }
 public DbSet<Settings> Settings { get; set; }
 public DbSet<ApiResourceEntity> ApiResources { get; set; }
....

数据库上下文定义

serviceCollection.AddDataProtection()
                .SetApplicationName("MyAPP")
                .PersistKeysToDbContext<ApplicationDbContext>()
                .ProtectKeysWithDpapiNG();

**已编辑：**我对该代码进行了注解，并且迁移已通过，因此问题是OnModelCreating（ModelBuilder modelBuilder）方法上的以下代码：

foreach (var entityType in modelBuilder.Model.GetEntityTypes())
            {
                foreach (var property in entityType.GetProperties())
                {
                    var attributes = property.PropertyInfo.GetCustomAttributes(typeof(EncryptedAttribute), false);
                    if (attributes.Any())
                    {
                        property.SetValueConverter(new EncryptedConverter(_dataProtectionProvider));
                    }
                }
            }

任何想法都可能是有帮助的。