"Message=unknown error: cannot focus element" while executing tests through Selenium, ChromeDriver and Chrome

I am trying to send key for a drop down list in google chrome browser but i am receiving this error

OpenQA.Selenium.WebDriverException
  HResult=0x80131500
  Message=unknown error: cannot focus element
  (Session info: chrome=68.0.3440.106)
  (Driver info: chromedriver=2.40.565498 (ea082db3280dd6843ebfb08a625e3eb905c4f5ab),platform=Windows NT 10.0.17134 x86_64)
  Source=WebDriver
  StackTrace:
   at OpenQA.Selenium.Remote.RemoteWebDriver.UnpackAndThrowOnError(Response errorResponse)
   at OpenQA.Selenium.Remote.RemoteWebDriver.Execute(String driverCommandToExecute, Dictionary`2 parameters)
   at OpenQA.Selenium.Remote.RemoteWebElement.Execute(String commandToExecute, Dictionary`2 parameters)
   at OpenQA.Selenium.Remote.RemoteWebElement.SendKeys(String text)
   at BnI.UITests.Register.TheOfficialInfoValidTest() in C:\Users\me\UITests\Register.cs:line 382

This is my method :

driver.FindElement(By.XPath("(.//*[normalize-space(text()) and normalize-space(.)='Country:'])[1]/following::span[2]")).SendKeys("USA");

This how its look in html :

<div _ngcontent-c4="" class="col-xs-8 no-padding-sides ng-star-inserted" style="">
   <kendo-dropdownlist _ngcontent-c4="" class="custom-dropdown k-widget k-dropdown k-header ng-pristine ng-invalid ng-touched" formcontrolname="countryId" dir="ltr">
      <span role="listbox" unselectable="on" class="k-dropdown-wrap k-state-default" id="k-d0697a91-baeb-4960-bfc1-c023903c1159" dir="ltr" readonly="false" tabindex="0" aria-disabled="false" aria-readonly="false" aria-haspopup="true" aria-expanded="false" aria-owns="dbfc0894-a4f5-4f1b-881f-1d88ccdc6002" aria-activedescendant="f65cbfa2-6280-4a84-908b-ba11da75d59d-undefined">
         <span unselectable="on" class="k-input">
            <!----><!---->Select Country ...
         </span>
         <span unselectable="on" class="k-select"><span class="k-i-arrow-s k-icon"></span></span><!---->
      </span>
      <!----><!---->
   </kendo-dropdownlist>
</div>

This is the XPath :

xpath=(.//*[normalize-space(text()) and normalize-space(.)='Country:'])[1]/following::span[2]

This how dropdownlist value look like if i want to click on it using selenium IDE because this value is retrieved from database :

1. First i clicked on the dropdownlist
2. Second i selected the country

Is there another way to add value by keyboard in selenium instead of send key ?

As per the HTML you have shared the target element is a <span> tag so you won't be able to invoke SendKeys() method. Instead you need to induce WebDriverWait for the desired element to be clickable and you can use either of the following solution:

new WebDriverWait(driver, TimeSpan.FromSeconds(10)).Until(ExpectedConditions.ElementToBeClickable(By.XPath("//span[@class='k-dropdown-wrap k-state-default' and @role='listbox']/span[@class='k-input']"))).Click();
//or
new WebDriverWait(driver, TimeSpan.FromSeconds(10)).Until(ExpectedConditions.ElementToBeClickable(By.XPath("//span[@class='k-dropdown-wrap k-state-default' and @role='listbox']//span[@class='k-select']"))).Click();