New transaction is not allowed because there are other threads running in the session

I am getting an error

New transaction is not allowed because there are other threads running in the session

while running this code in C# entity framework,

foreach (var pFiles in projectFilesList)
{
    ProjectFiles projectFile = (ProjectFiles)pFiles;
    projectFile.Status = Constants.ProjectFiles_ERROR;
    projectFile.DateLastUpdated = DateTime.Now;
    context.SaveChanges();
}


//projectFilesList is a list collection

any ideas what can be the issue?

Asked by:- vikas_jk

: 11134 At:- 6/11/2017 7:39:36 AM

C# asp.net mvc linq

did you tried putting your context.SaveChanges(); outside freach loop? 2

By : manish - at :- 6/11/2017 7:50:51 AM

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3 Answers

Answered by:- pika

here i think proejctFilesList isn't a collection of objects, it is an Enumerator that can return objects, what you need to do is add .Tolist() to it, and it should work like

foreach (var pFiles in projectFilesList.ToList())
{
    ProjectFiles projectFile = (ProjectFiles)pFiles;
    projectFile.Status = Constants.ProjectFiles_ERROR;
    projectFile.DateLastUpdated = DateTime.Now;
    context.SaveChanges();
}

also, Calling SaveChanges() withing foreach of ToList() or ToArray() is fine for small data sets, but when you have thousands of rows, you will be consuming a large amount of memory.

It's better to load the rows in chunks or keep the SaveChanges() outside the foreach as manish suggested.

At:- 6/11/2017 11:41:49 AM Updated at:- 12/9/2022 7:20:27 AM

good answer, thank you 0

By : vikas_jk - at :- 6/11/2017 11:46:27 AM

The issue is that we can't call SaveChanges while you're still pulling results from the DB. Therefore another solution is just to save changes once the loop has completed. 0

By : Vinnu - at :- 12/9/2022 3:47:00 PM

comment to above answer

Answered by:- bhanu

You may also get this error when you are calling context.SaveChanges() inside the foreach loop in C#.

It is better to context.SaveChanges(), once you are done with foreach loop, for example:

foreach (var pFiles in projectFilesList.ToList())
{
    ProjectFiles projectFile = (ProjectFiles)pFiles;
    projectFile.Status = Constants.ProjectFiles_ERROR;
    projectFile.DateLastUpdated = DateTime.Now;  
}

//call SaveChanges Here
context.SaveChanges();

It is better make all changes (which Entity Framework will cache) and then save all of the changes at once, by calling SaveChanges() outside the loop.

It will also improve performance, because you will not be calling .SaveChanges() after one small change ( after completing each loop), but it will save all changes at once, which improves performance.

At:- 4/14/2021 8:28:19 AM