System.ArgumentException: An item with the same key has already been added. Key: NextExecution

[Lexiphan]

This bug prevents running all recurring jobs, and also prevents me to open "Recurrent" page. I was able to cure it by re-creating of the database.

This bug is reproduced on the latest version of this package and the latest version of Hangfire.Core.

An unhandled exception has occurred while executing the request.

System.ArgumentException: An item with the same key has already been added. Key: NextExecution
   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at System.Linq.Enumerable.SpanToDictionary[TSource,TKey,TElement](ReadOnlySpan`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector)
   at Hangfire.PostgreSql.PostgreSqlConnection.<>c__DisplayClass18_0.<GetAllEntriesFromHash>b__0(DbConnection connection)
   at Hangfire.PostgreSql.PostgreSqlStorage.UseConnection[T](DbConnection dedicatedConnection, Func`2 func)
   at Hangfire.PostgreSql.PostgreSqlConnection.GetAllEntriesFromHash(String key)
   at Hangfire.Storage.StorageConnectionExtensions.GetRecurringJobDtos(IStorageConnection connection, IEnumerable`1 ids) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Storage\\StorageConnectionExtensions.cs:line 94
   at Hangfire.Storage.StorageConnectionExtensions.GetRecurringJobs(JobStorageConnection connection, Int32 startingFrom, Int32 endingAt) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Storage\\StorageConnectionExtensions.cs:line 72
   at Hangfire.Dashboard.Pages.RecurringJobsPage.Execute() in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Dashboard\\Pages\\RecurringJobsPage.cshtml:line 28
   at Hangfire.Dashboard.RazorPage.TransformText(String body) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Dashboard\\RazorPage.cs:line 179
   at Hangfire.Dashboard.RazorPage.ToString() in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Dashboard\\RazorPage.cs:line 103
   at Hangfire.Dashboard.RazorPageDispatcher.Dispatch(DashboardContext context) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Dashboard\\RazorPageDispatcher.cs:line 38
   at Hangfire.Dashboard.AspNetCoreDashboardMiddleware.Invoke(HttpContext httpContext) in C:\\projects\\hangfire-525\\src\\Hangfire.AspNetCore\\Dashboard\\AspNetCoreDashboardMiddleware.cs:line 99
   at Microsoft.AspNetCore.Builder.Extensions.MapMiddleware.InvokeCore(HttpContext context, PathString matchedPath, PathString remainingPath)
...

Stack trace when a scheduled job is about to be run:

Execution RecurringJobScheduler is in the Failed state now due to an exception, execution will be retried in no more than 00:00:25

System.ArgumentException: An item with the same key has already been added. Key: NextExecution
   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at System.Linq.Enumerable.SpanToDictionary[TSource,TKey,TElement](ReadOnlySpan`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector)
   at Hangfire.PostgreSql.PostgreSqlConnection.<>c__DisplayClass18_0.<GetAllEntriesFromHash>b__0(DbConnection connection)
   at Hangfire.PostgreSql.PostgreSqlStorage.UseConnection[T](DbConnection dedicatedConnection, Func`2 func)
   at Hangfire.PostgreSql.PostgreSqlConnection.GetAllEntriesFromHash(String key)
   at Hangfire.RecurringJobExtensions.GetRecurringJob(IStorageConnection connection, String recurringJobId) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\RecurringJobExtensions.cs:line 49
   at Hangfire.Server.RecurringJobScheduler.TryEnqueueBackgroundJob(BackgroundProcessContext context, IStorageConnection connection, String recurringJobId, DateTime now) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Server\\RecurringJobScheduler.cs:line 288
   at Hangfire.Server.RecurringJobScheduler.<>c__DisplayClass27_0.<EnqueueNextRecurringJobs>b__0(IStorageConnection connection) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Server\\RecurringJobScheduler.cs:line 248
   at Hangfire.Server.RecurringJobScheduler.UseConnectionDistributedLock[T](JobStorage storage, Func`2 action) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Server\\RecurringJobScheduler.cs:line 425
   at Hangfire.Server.RecurringJobScheduler.EnqueueNextRecurringJobs(BackgroundProcessContext context) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Server\\RecurringJobScheduler.cs:line 203
   at Hangfire.Server.RecurringJobScheduler.Execute(BackgroundProcessContext context) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Server\\RecurringJobScheduler.cs:line 176
   at Hangfire.Server.BackgroundProcessDispatcherBuilder.ExecuteProcess(Guid executionId, Object state) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Server\\BackgroundProcessDispatcherBuilder.cs:line 82
   at Hangfire.Processing.BackgroundExecution.Run(Action`2 callback, Object state) in C:\\projects\\hangfire-525\\src\\Hangfire.Core\\Processing\\BackgroundExecution.cs:line 118

I've saved the "broken database" and can provide it for the investigation.