SQL Server procedure has too many arguments specified - asp.net

Question

I get the error
Procedure or function has to many arguments specified
but only sometimes. It's a REST API and cellphones call this function to validate the user. Today it's onli 1-2 cellphones and they make the call every second minute.
It works well most times but sometimes I get this error code.
To see what's wrong, I've made a small loop that gathers the parameters into a string. And sometimes they are two #GUID and #Datum and sometimes repeat themselves.
Here is the VB code:
Public Shared Sub validatePhone(secretKey As String, ByRef _RS As phoneData, Fnr As Integer)
Dim connStr As String = System.Configuration.ConfigurationManager.AppSettings("ConnStringSQL")
Dim Conn As SqlConnection = New System.Data.SqlClient.SqlConnection(connStr)
Dim _theString As New System.Text.StringBuilder
Try
_RS.message = ""
_RS.status = True
Dim Status As Integer = 0
Dim _GUID As Guid = New Guid(secretKey)
Try
Conn.Open()
Catch ex As Exception
End Try
cmd.Connection = Conn
Apt.SelectCommand = cmd
cmd.CommandType = CommandType.StoredProcedure
cmd.CommandText = "API2017_checkPhone"
cmd.Parameters.Clear()
cmd.Parameters.Add("#GUID", SqlDbType.UniqueIdentifier).Value = _GUID
cmd.Parameters.Add("#Datum", SqlDbType.SmallDateTime).Value = Now
For Each item As SqlParameter In cmd.Parameters
_theString.Append(item.ParameterName & ";")
Next
Apt.Fill(ds, "DataCheckPhone")
If ds.Tables("DataCheckPhone").Rows.Count > 0 Then
With ds.Tables("DataCheckPhone").Rows(0)
Status = .Item("spStatus")
If Status = 0 Then
_RS.Namn = .Item("Namn")
_RS.SalesID = .Item("SalesID")
_RS.Anlaggning = .Item("Anlaggning")
_RS.Anlnr = .Item("Anlnr")
Funktions.URLEncodeStr(_RS.Namn)
Funktions.URLEncodeStr(_RS.Anlaggning)
End If
End With
Else
Dim _Lnum As Integer
Funktions.Logg(Fnr & ": " & "Fatal error", 999, _Lnum, 0)
_RS.message = "Error 999:" & _Lnum.ToString
Return
End If
Catch ex As Exception
_RS.status = False
_RS.Anlaggning = Nothing
_RS.Anlnr = 0
_RS.Namn = Nothing
_RS.SalesID = Nothing
Dim _Lnum As Integer
Funktions.Logg(Fnr & ": " & ex.Message & "{" & _theString.ToString & "}", 999, _Lnum, 0)
_RS.message = "Error 999:" & _Lnum.ToString
Finally
ds.Tables.Clear()
Try
ds.Tables("DataCheckPhone").Dispose()
Catch ex As Exception
End Try
End Try
Try
Conn.Close()
Conn.Dispose()
Catch ex As Exception
End Try
End Sub
And here is the stored procedure:
ALTER PROCEDURE [dbo].[API2017_checkPhone]
#GUID as uniqueidentifier,
#Datum as smalldatetime
AS
DECLARE #Status AS INT
DECLARE #Anlaggning AS NVARCHAR(50)
DECLARE #Namn AS NVARCHAR(50)
DECLARE #Anlnr AS INT
DECLARE #SalesID AS uniqueidentifier
DECLARE #LockedSalesman AS BIT
DECLARE #LockedAnlaggning AS BIT
SET #Status = 0
IF EXISTS (SELECT * FROM KK2017_connectedPhones WHERE [guid] = #guid)
BEGIN
SET #status = 0
SET #salesID = (SELECT salesID FROM KK2017_connectedPhones
WHERE [guid] = #guid)
SET #Anlnr = (SELECT anlnr FROM KK2017_Säljare WHERE salesID = #salesID)
SET #Namn = (SELECT Namn FROM KK2017_Säljare WHERE salesID = #salesID)
SET #Anlaggning = (SELECT namn FROM KK2017_Anlaggning WHERE anlnr = #Anlnr)
SET #LockedSalesman = (SELECT locked FROM KK2017_Säljare WHERE salesID = #salesID)
UPDATE KK2017_Säljare
SET inloggad = #Datum
WHERE salesID = #SalesID
IF #LockedSalesman = 1
BEGIN
SET #Status = 2
END
SET #LockedAnlaggning = (SELECT locked FROM KK2017_Anlaggning
WHERE AnlNr = #Anlnr)
IF #LockedAnlaggning = 1
BEGIN
SET #status = 3
END
END
ELSE
SET #status = 1
SELECT
#Status AS spStatus,
#Anlaggning AS Anlaggning,
#anlnr AS anlnr,
#Namn AS namn,
#SalesID AS salesID
I must have done something wrong but can not see it.
If anyone has a proposal, I would be grateful.
/Claes

Answer 1

You have a threading issue because you have defined cmd as shared, which means there is only one instance servicing all of the incoming requests. Sometimes two threads are in the process of adding parameters at the same time, and both threads end up with four, hence the error.
The standard pattern here would be declare cmd as a local variable, and instantiate a new instance each time the function is called. The overhead to this is negligible.
Also, avoid shared variables in multithreaded applications (such as web services). There is only one copy of the variable for all users and all threads, and 99% of the time that is not what you actually want. For the other 1% usually you'd use application variables or HttpCache. In this case you should use a local variable.