We're going to need a full reproduction case; ruby code, and HTML+javascript+css or
a live URL we can visit, to fix this.

<<<< HTML >>>>

<td align="center">
<a onmouseout="nd(); return true;" onmouseover="overlib('Delete')" href="javascript:localDelete('object')">
<img width="16" height="16" border="0" src="/Images/Common/delete.gif">
</a>
</td>

<<<<JS>>>

function localDelete(item)
{
var lf = top.frames[1].frames[1].frames[1].document.localForm;
if (!confirm("Are you sure you want to\npermanently remove this " + item + "?"))
{
lf.reset();
}
else
{

onSubmitHandler();
lf.CMD.value = "delete";
lf.submit();
}
} 
<<< HTML Form >>>

<form method="POST" target="middle" enctype="multipart/form-data" action="services.origin.FileAction.action"
name="localForm">
<input type="hidden" value="true" name="postback">
<input type="hidden" value="" name="FIELD">
<input type="hidden" value="" name="SORT">
<input type="hidden" value="" name="pageName">
<input type="hidden" value="modify" name="CMD">




<<<<Ruby scripts>>>>


      del_button = @driver.find_element(:xpath,'/html/body/table/tbody/tr/td/table/tbody/tr/td[2]/a')
        #@driver.action.move_to(del_button).perform
        if @browser_type == 'firefox'
            @driver.manage.timeouts.page_load = 3
            @driver.manage.timeouts.script_timeout = 2
        end
        begin
            del_button.click()
        rescue Selenium::WebDriver::Error::ScriptTimeOutError => e
        #rescue Selenium::WebDriver::Error::TimeOutError => e
        #rescue Timeout::Error => e
        end
        #@driver.find_element(:xpath,'/html/body/table/tbody/tr/td/table/tbody/tr/td[2]/a').send_keys("\n")
        #@driver.execute_script('localDelete(\'object\')')
        windows = @driver.window_handles
        windows.each { |win| puts win}
        #frs = @driver.find_elements(:tag_name,'frame')
        #frs.each { |fr| puts fr}
        begin
            puts 'Switching to alert'
            a = @driver.switch_to.alert
            #puts a.text
            a.accept
        rescue Selenium::WebDriver::Error::NoAlertPresentError => e
        end


<<<<On Windows: >>>

{b0dfbf60-204d-47c6-b58e-83e6f709127a}
Switching to alert
[remote server] org.openqa.selenium.remote.RemoteWebDriver$RemoteTargetLocator(RemoteWebDriver.java):698:in
`alert': java.lang.Boolean cannot be cast to java.lang.String (java.lang.ClassCastException)
(Selenium::WebDriver::Error::UnknownError)
    from [remote server] org.openqa.selenium.support.events.EventFiringWebDriver$EventFiringTargetLocator(EventFiringWebDriver.java):589:in
`alert'
    from [remote server] org.openqa.selenium.remote.server.handler.GetAlertText(GetAlertText.java):32:in
`call'
    from [remote server] org.openqa.selenium.remote.server.handler.GetAlertText(GetAlertText.java):1:in
`call'
    from [remote server] java.util.concurrent.FutureTask$Sync():-1:in `innerRun'
    from [remote server] java.util.concurrent.FutureTask():-1:in `run'
    from [remote server] java.util.concurrent.ThreadPoolExecutor$Worker():-1:in `runTask'
    from [remote server] java.util.concurrent.ThreadPoolExecutor$Worker():-1:in `run'
    from [remote server] java.lang.Thread():-1:in `run'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/response.rb:52:in
`assert_ok'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/response.rb:15:in
`initialize'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/http/common.rb:59:in
`new'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/http/common.rb:59:in
`create_response'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/http/default.rb:64:in
`request'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/http/common.rb:40:in
`call'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/bridge.rb:594:in
`raw_execute'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/bridge.rb:572:in
`execute'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/bridge.rb:139:in
`getAlertText'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/common/alert.rb:9:in
`initialize'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/common/target_locator.rb:76:in
`new'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/common/target_locator.rb:76:in
`alert'
    from ./cms_wb_api.rb:357:in `delete'
    from ./cms_wb_api.rb:370:in `del_nas'
    from test-cms.rb:51

<<<<On Ubuntu, localhost >>>

remote server] file:///tmp/webdriver-profile20120319-21364-115eaoc/extensions/fxdriver@googlecode.com/components/command_processor.js:9434:in
`unknown': Timed out waiting for page load. (Selenium::WebDriver::Error::TimeOutError)
    from [remote server] file:///tmp/webdriver-profile20120319-21364-115eaoc/extensions/fxdriver@googlecode.com/components/command_processor.js:8668:in
`unknown'
    from [remote server] file:///tmp/webdriver-profile20120319-21364-115eaoc/extensions/fxdriver@googlecode.com/components/command_processor.js:8674:in
`unknown'
    from [remote server] file:///tmp/webdriver-profile20120319-21364-115eaoc/extensions/fxdriver@googlecode.com/components/command_processor.js:8585:in
`unknown'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/response.rb:52:in
`assert_ok'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/response.rb:15:in
`initialize'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/http/common.rb:59:in
`new'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/http/common.rb:59:in
`create_response'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/http/default.rb:64:in
`request'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/http/common.rb:40:in
`call'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/bridge.rb:594:in
`raw_execute'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/bridge.rb:572:in
`execute'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/remote/bridge.rb:354:in
`clickElement'
    from /usr/lib/ruby/gems/1.8/gems/selenium-webdriver-2.20.0/lib/selenium/webdriver/common/element.rb:34:in
`click'
    from ./cms_wb_api.rb:344:in `delete'
    from ./cms_wb_api.rb:370:in `del_nas'
    from test-cms.rb:51

anyone could help ?
Still have this issue with 2.21.

We're facing the same issue in Java:
{code}
java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String
        at org.openqa.selenium.remote.RemoteWebDriver$RemoteTargetLocator.alert(RemoteWebDriver.java:688)
{code}
Selenium version: 2.16.1
OS: Linux
Browser: Firefox 9.0.1

seems to work with v.2.22.0 and FF 12

I see this same issue using Java.

Alert alert = browser.switchTo().alert();

Exception:
java.lang.Boolean cannot be cast to java.lang.String

org.openqa.selenium.remote.RemoteWebDriver$RemoteTargetLocator.alert(RemoteWebDriver.java:734)


WD version: 2.22.0
OS: Linux
Browser: FF 3.6.24

Issue is reproduced using Java for me as well.
WD version: 2.25
OS: Linux
Browser: FF 

Here is a part of WD code which cause this issue (org.openqa.selenium.remote.RemoteWebDriver):

public Alert alert() {
Response response = RemoteWebDriver.this.execute("getAlertText");
return new RemoteWebDriver.RemoteAlert(RemoteWebDriver.this, (String)response.getValue());
}

Reproduced Issue

WD: 2.26
OS: Win 7
Browser: FF 12

public Alert alert() {
      Response response = execute(DriverCommand.GET_ALERT_TEXT);
      return new RemoteAlert((String) response.getValue());
    }

Hi ,

I am facing the same issue when switching to alert.This is happening 2 or 3 times out
of 200 times.

WD:2.25
OS:Windows server 2008
Browser:FF12

please help me how can i fix this.

java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String
    at org.openqa.selenium.remote.RemoteWebDriver$RemoteTargetLocator.alert(RemoteWebDriver.java:775)

I am seeing the same issue (ClassCastException in the same code block as above)

WD: 2.28
FF: 17
OS: Win 7, Win 2008

I should note this is with the Java driver.

In selenium 2.30 the error message will contain more information, we hope to be able
to  understand the root cause then.

For what it's worth, I've been able to consistently reproduce the issue in my environment
by executing two separate actions that cause alerts, and calling selenium.getAlert()
after each action.  The second call to getAlert is throwing the ClassCastException.

@JimRAnderson: Would you please share a piece of code instead of text description? What
do you mean by "executing two separate actions that cause alerts"?

Can anybody having the issue retest it and tell us the diagnostic message that should
contain more details now?

Closing due to inactivity. Please ask to reopen if the issue is still actual.

I see this same issue using Java. Happens when 2 test cases run sequentially. There
is no error where running each test separately.

Alert alert = browser.switchTo().alert();

Exception:
ava.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String at
org.openqa.selenium.remote.RemoteWebDriver$RemoteAlert.getText(RemoteWebDriver.java:867)

866 public String getText() {
867      return (String) execute(DriverCommand.GET_ALERT_TEXT).getValue();
868 }

WD version: 2.25.0
OS: Windows 7 Professional
Browser: FF 22.0

@badong2210: The latest version of Selenium is 2.35

This issue occurred with Selenium 2.40.0 (Java) and Firefox 25.0.1 (Windows) with local
execution.

An UnhandledAlertException was thrown during the test-execution (findElement) because
there was a "long running script" alert.

The a test fails, we are calling "driver.switchTo().alert()" to check if there is an
alert present and try to log out the text if an alert is present "LOGGER.log(Level.WARNING,
"Alert with text \"{0}\" was present and will be dismissed now...", alert.getText());"

Issue still exists in Selenium 2.42.2, it is not fixed!

java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String
    at org.openqa.selenium.remote.RemoteWebDriver$RemoteAlert.getText(RemoteWebDriver.java:918)

thrown in:
    public String getText() {
      return (String) execute(DriverCommand.GET_ALERT_TEXT).getValue();
    }

whereas here it is used without cast, but using toString()

  public String getCurrentUrl() {
    return execute(DriverCommand.GET_CURRENT_URL).getValue().toString();
  }

which would probably solve the problem at least regarding the exception. Why it's a
boolean in the first place, I have no idea, the alert window clearly contains a lot
of text.

@asbytes: Please provide a sample page and a scenario to reproduce the issue.

I get the same issue on selenium 2.43.1 and Firefox 24ESR.

- Load the page http://www.tacobell.com/tacobell/store-locator/
- fill the input element .//*[@id='findUsZip'] with the value "OR"
- click on the eleemnt .//*[@id='findUsZipGo'] to submit the form
- An alert will popup after a few seconds
- Alert alert = browser.switchTo().alert().getText()

will result in java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String

2.44 as well.