Element not found - Selenium - selenium

Question

I have written a piece of code to login into an application which is working fine. Now I have to click an add button, and I have tried it by Id, XPath, ClassName but it just gives me the exception of element not found. I thought I should apply an explicit wait, but it also did not work. Please check my code below:
public static void Login()
{
Browser.Url = "http://example.com";
_username = Browser.FindElement(By.Id("UserName"));
var password = Browser.FindElement(By.Id("Password"));
var loginbtn = Browser.FindElement(By.ClassName("btn-primary"));
_username.SendKeys("admin");
password.SendKeys("123");
loginbtn.Click();
var supplierTab = Browser.FindElement(By.Id("mainSupplier"));
supplierTab.Click();
WebDriverWait wait = new WebDriverWait(Browser, TimeSpan.FromSeconds(20));
IWebElement myDynamicElement = wait.Until<IWebElement>((d) =>
{
try
{
return d.FindElement(By.Id("btnAddSupplier_SupplierForm"));
}
catch
{
return null;
}
});
var addbtn = Browser.FindElement(By.Id("btnAddSupplier_SupplierForm"));
addbtn.Click();
}
This always gives an exception on the second last line of code that element not found.
Here is the HTML:

Answer 1

Try the following
public static void Login()
{
Browser.Url = "http://example.com";
_username = Browser.FindElement(By.Id("UserName"));
var password = Browser.FindElement(By.Id("Password"));
var loginbtn = Browser.FindElement(By.ClassName("btn-primary"));
_username.SendKeys("admin");
password.SendKeys("123");
loginbtn.Click();
//I think you have mentioned the iframe exist and assuming the element is inside the iframe do the following. If not skip the SwitchTo() part
//you can use name, css to identify the iframe
Browser.SwitchTo().Frame(Browser.FindElement(By.XPath("xpath for the iframe")));
var supplierTab = Browser.FindElement(By.Id("mainSupplier"));
supplierTab.Click();
WebDriverWait wait = new WebDriverWait(Browser, TimeSpan.FromSeconds(20));
IWebElement myDynamicElement = wait.Until<IWebElement>((d) =>
{
return d.FindElement(By.Id("btnAddSupplier_SupplierForm"));
});
//if you think the id is not unique try using xpath or css
//even though you added an explicit wait you never used it
myDynamicElement.Click();
}

Answer 2

Sometimes the element will be existing in the source code but will not be visible for selenium to perform a click operation. Try the below code which will wait until the element is visible:
WebDriverWait wait = new WebDriverWait(_driver, TimeSpan.FromSeconds(20));
IWebElement element = wait.Until(
ExpectedConditions.ElementIsVisible(By.Id("btnAddSupplier_SupplierForm")));
element.Click();

Answer 3

Not sure if this would help, but try calling this function before you click on Add button:
void waitForPageLoad(WebDriver driver)
{
ExpectedCondition<Boolean> pageLoadCondition = new ExpectedCondition<Boolean>() {
public Boolean apply(WebDriver driver) {
return ((JavascriptExecutor)driver).executeScript("return document.readyState").equals("complete");
}
};
wait.until(pageLoadCondition);
}

Answer 4

A NoSuchElementException is thrown when the locating mechanism used is not available in the dom.
A TimeoutException is thrown when your expected condition fails to be true within the time limit. An expected condition can be anything, (exists,visibility,attribute value etc...).
First you want to figure out if the element's locating mechanism you are using is indeed not found in the dom. Here is a good way to manually find out.
Open chrome and navigate to the page.
Open chrome dev tools and click on the console tab.
In the text box type $x("//*[#id='btnAddSupplier_SupplierForm']") and hit enter. This will run an xpath query, basically you are looking for any element that has an id attribute with value "btnAddSupplier_SupplierForm".
If an element appears in the console and is the correct element then it's likely that you are trying to find an element in the dom before the dom is finished loading. If no element appears in the console then you have a bad locator.
Please report your findings.