Getting InvalidOperationException when using PerformanceCounters

Question

Getting:

Exception thrown: 'System.InvalidOperationException' in System.dll

Additional information:

Category does not exist.

The code :

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication8
{
public partial class Form1 : Form
{
    PerformanceCounter cpuCounter;
    PerformanceCounter ramCounter;
    public Form1()
    {
        InitializeComponent();
    }
    int timeX = 0;
    private void timer1_Tick(object sender, EventArgs e)
    {
        cpuCounter = new PerformanceCounter();
        cpuCounter.CategoryName = "Processor";
        cpuCounter.CounterName = "% Processor Time";
        cpuCounter.InstanceName = "_Total";


        float cpuUsage = 0.00F;
        cpuCounter.NextValue();
        cpuUsage = cpuCounter.NextValue();
        textBox1.Text = cpuUsage.ToString();


        ramCounter = new PerformanceCounter("Memory", "Available MBytes");
        float ram = ramCounter.NextValue();
        textBox2.Text = ram.ToString();

        chart1.Series["CPU Usage"].Points.AddXY(timeX, (int)cpuUsage);
        chart2.Series["Memory Use"].Points.AddXY(timeX, (int)ram);

    }

    private void button1_Click(object sender, EventArgs e)
    {
       timer1.Start();
    }

    private void button2_Click(object sender, EventArgs e)
    {
        timer1.Stop();
    }
}
}

Getting errors on every .nextValue();

I have tried adding Processor Information in CategoryName, but doesn't help either.

EDIT: @Jim this is my code after making your changes :

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Diagnostics;
namespace WindowsFormsApplication12
{
public partial class Form1 : Form
{
    PerformanceCounter cpuCounter;
    PerformanceCounter ramCounter;

    public Form1()
    {
        InitializeComponent();

        InitializeCounters();
    }

    private void InitializeCounters()
    {
        cpuCounter = new PerformanceCounter();
        cpuCounter.CategoryName = "Processor";
        cpuCounter.CounterName = "% Processor Time";
        cpuCounter.InstanceName = "_Total";

       // ramCounter = new PerformanceCounter("Memory", "Available MBytes");
    }

    int timeX = 0;
    private void timer1_Tick(object sender, EventArgs e)
    {
        float cpuUsage = 0.00F;
        cpuUsage = cpuCounter.NextValue();
        textBox1.Text = cpuUsage.ToString();

        float ram = ramCounter.NextValue();
        textBox2.Text = ram.ToString();

        // Your chart stuff
        //chart1.Series["CPU Usage"].Points.AddXY(timeX, (int)cpuUsage);
        //chart2.Series["Memory Use"].Points.AddXY(timeX, (int)ram);
    }

    private void button1_Click(object sender, EventArgs e)
    {
        timer1.Start();
    }

    private void button2_Click(object sender, EventArgs e)
    {
        timer1.Stop();
    }
}

}

Answer 1

You are creating new performance counters every time the timer ticks, you only need to initialize the counters once.

Form1 Code Behind

PerformanceCounter cpuCounter;   
PerformanceCounter ramCounter;

public Form1()
{
    InitializeComponent();

    InitializeCounters();
}

private void InitializeCounters()
{
    cpuCounter = new PerformanceCounter();
    cpuCounter.CategoryName = "Processor";
    cpuCounter.CounterName = "% Processor Time";
    cpuCounter.InstanceName = "_Total";

    ramCounter = new PerformanceCounter("Memory", "Available MBytes");
}

int timeX = 0;
private void timer1_Tick(object sender, EventArgs e)
{        
    float cpuUsage = 0.00F;
    cpuUsage = cpuCounter.NextValue();
    textBox1.Text = cpuUsage.ToString();
   
    float ram = ramCounter.NextValue();
    textBox2.Text = ram.ToString();

    // Your chart stuff
    //chart1.Series["CPU Usage"].Points.AddXY(timeX, (int)cpuUsage);
    //chart2.Series["Memory Use"].Points.AddXY(timeX, (int)ram);
}

private void button1_Click(object sender, EventArgs e)
{
    timer1.Start();
}

private void button2_Click(object sender, EventArgs e)
{
    timer1.Stop();
}

Side note:

Also Dispose the counters when not using them anymore. Maybe on Form Closing event.

cpuCounter.Dispose();
ramCounter.Dispose();

---

Result

---

Case of an error

If my example still throws an error, this is most probably because one or more performance counters on your system are corrupted.

Rebuild all performance counters:

• Open command prompt (with Admin privileges)
• Run command: lodctr /R

The message:

Info: Successfully rebuilt performance counter setting ...

will appear on success.

In case you receive the message:

Unable to rebuild performance counter setting from system backup store, error code is 2

Possible solutions:

• Close all running programs
• Make sure you use lodctr /R with uppercase R
• If in directory system32 move to directory SysWOW64 (with cd.. > cd syswow64) and retry the lodctr /R command in this directory