Selenium TypeError dead object

Question

I tried to run the following selenium test case (I am using Selenium 2.5.0, Firefox 27), but keep getting the following error:

[error] Unexpected Exception: TypeError: can't access dead object. fileName -> chrome://selenium-ide/content/selenium-core/scripts/selenium-api.js, lineNumber -> 1306, columnNumber -> 8

I searched online, but only people got similar error, I wonder if anyone could give a hint for this problem. I list my test case as follows, and my error comes to the last step, where I try to consume an alert message:

<tr>
    <td>selectWindow</td>
    <td>name=menu</td>
    <td></td>
</tr>
<tr>
    <td>click</td>
    <td>xpath=(//input[@id='I-3'])[33]</td>
    <td></td>
</tr>
<tr>
    <td>waitForPopUp</td>
    <td></td>
    <td>30000</td>
</tr>
<tr>
    <td>selectWindow</td>
    <td>CourseReversalDelete</td>
    <td></td>
</tr>
<tr>
    <td>selectFrame</td>
    <td>name=content</td>
    <td></td>
</tr>
<tr>
    <td>clickAndWait</td>
    <td>name=Delete</td>
    <td></td>
</tr>
<tr>
    <td>verifyText</td>
    <td>id=alertMessageText</td>
    <td>Profile Starts successfully Deleted</td>
</tr>
<tr>
    <td>click</td>
    <td>id=alertMessageButton</td>
    <td></td>
</tr>

Answer 1

I've been having the same problem (I am using Selenium 2.5.0, Firefox 27) and it always occur when using multiple "open" commands of a URL. I haven't been able to determine root cause, but have determined a workaround. By breaking into new cases before the error, I can eliminate it.

Far from ideal, but thought it may suffice until we can find a root cause.

Answer 2

my teamate got a solution, and we had a gues about what is happening behind selenium. It looks not firefox fault (https://blog.mozilla.org/addons/2012/09/12/what-does-cant-access-dead-object-mean/), nor could we do anything on firefox (I do not think it is a good idea to change firefox code to avoid the problem as someone recommended). the only thing left for us is to change our project code to avoid it. It worked fine, no such error ocured anymore. we suspect it is due to our code had alert message dialog which is named as "confirm", howvere, this name is used by firefox for its internal alert message, and it needs to be consumed by Selenium. So when Selenium found this message, it immediately consumed it, and later when Selenium test case required to click the alert meesage, it is a dead object. the solution for us is to rename the alert message in our project code as "confirmForm" , then the problem is solved. This si just our guess. I hope this idea is helpful for others.