Receiving error while updating a folder inside sharepoint list

Question

What my code does - runs through each folders present in a list, and if any of the folders are in the name with current year, then it shall be renamed, ie 2012 to 2012_Backup. Soon after it is renamed we will create a name folder named 2012 and I get error
here. Below is my code. Please suggest a work arround please.
for (int i = 0; i < additionalList.Folders.Count; i++)
                    if (additionalList.Folders[i].Folder.Name == Convert.ToString(DateTime.Now.Year))
                        oldFolder = targetList_additionalList.Folders[i];
                        oldFolder[Title] = Convert.ToString(DateTime.Now.Year) + backUp;
                        oldFolder.Update();
                        additionalList.Update();
SPListItem newfolder = targetList_additionalList.AddItem(workflowProperties.Item.Folder.ServerRelativeUrl, SPFileSystemObjectType.File);
                          newfolder[Title] = Convert.ToString(DateTime.Now.Year);
                   newfolder.Update();
                   targetList_additionalList.Update();
Error Details :
Microsoft.SharePoint.SPException: Invalid file name.
The file name you specified could not be used.  It may be the name of an existing file or directory, or you may not have permission to access the file.
Shameej

Answer 1

Hi shameej,
Based on the error message, the issue should be caused that the new folder is created before the old folder name change.
From your code sample, you seems to execute the code in workflow, if so, before the new folder item is created, add wait for sometime action, whether this can fix the issue?
if it isn't the issue, would you please help to provide more information about your code execution environment, in which type of project?
Thanks,
Qiao Wei
TechNet Community Support