Runtime error 52 Bad file or number and syntax error

[Pookiemeister]

This code runs inside a template workbook. When the workbook opens it will check and see if the following workbook name exists, if not, it will create a saved workbook copy with that name, otherwise it will open that workbook. I am not sure if this matters, but this file is saved to OneDrive. The error 52 message occurs on this line:

If Len(Dir(FilePath)) = 0 Then

and the syntax error occurs here: The following part of the code is highlighted in blue "C:\Users\"

Set wb1 = ActiveWorkbook.SaveCopyAs "C:\Users\" & Environ("username") & "\OneDrive - CompanyName\Desktop\" & CurrMonth & "'s WO Report.xlsm"

    Dim wb1 As Workbook
    Dim FilePath As String
 
    CurrMonth = Format(DateAdd("M", 0, Now), "MMMM")
 
    FilePath = ThisWorkbook.Path & "/" & CurrMonth & "'s WO Report.xlsm"
    If Len(Dir(FilePath)) = 0 Then
        Set wb1 = ActiveWorkbook.SaveCopyAs "C:\Users\" & Environ("username") & "\OneDrive - CompanyName\Desktop\" & CurrMonth & "'s WO Report.xlsm"
    Else
        Set wb1 = Workbooks.Open(FilePath)
    End If
   
    Set CheckForExistingWorkbooks = wb1

 

[rlv01]

FilePath = ThisWorkbook.Path & "/" & CurrMonth & "'s WO Report.xlsm"

Is there a reason you have a forward slash in the above instead of the normally expected backslash ("\")?