I'have the same exception:

com.thoughtworks.selenium.SeleniumException: ERROR: Couldn't delete cookie __noteCook
    at 
com.thoughtworks.selenium.HttpCommandProcessor.throwAssertionFailureExceptionOrError(
HttpCommandProcessor.java:97)
    at 
com.thoughtworks.selenium.HttpCommandProcessor.doCommand(HttpCommandProcessor.java:91
)
    at 
com.thoughtworks.selenium.DefaultSelenium.deleteAllVisibleCookies(DefaultSelenium.jav
a:663)
    at 
ru.selftrip.crawler.SeleniumCrawler.deleteAllVisibleCookies(SeleniumCrawler.java:552)
    at 
ru.selftrip.crawler.impl.AirBalticDailyCrawler.getFlights(AirBalticDailyCrawler.java:
27)
    at ru.selftrip.crawler.ScheduledCrawler.crawl(ScheduledCrawler.java:68)
    at ru.selftrip.crawler.CrawlerApp.main(CrawlerApp.java:53)

Same problem here too, running via the IDE: [error] Couldn't delete cookie __utma 

I got this issue both IDE(1.0.8) and RC(2.0a7)
as the selenium RC server's log:
----------
13:42:11.701 INFO - Command request: deleteAllVisibleCookies[, ] on session b85cc414d7fa47f88e61ecd4be4ff438
13:42:11.739 INFO - Got result: OK on session b85cc414d7fa47f88e61ecd4be4ff438
----------
But actually ,it doesn't work.

Is this an issue in the latest release?

I need a publicly availably site that triggers this -- otherwise I'm going to close
it. I don't doubt the possibility of a bug in the cookie code, but without a test case
it is non-reproducable.

Oh, and try with at least 1.0.10.

site http://www.searsopticalcontacts.com
same issue on 1.0.10
a cookie there has % in name

Selenium.prototype.doDeleteAllVisibleCookies() uses BrowserBot.prototype.getAllCookieNames()
performs a decodeURIComponent() operation on the name of the cookie.

This turns drugstore%2Efish into drugstore.fish, a non-existent cookie name.

The broken name will be returned in the list, and later used by BrowserBot.prototype.recursivelyDeleteCookie(),
which throws the aforementioned error: throw new SeleniumError("Couldn't delete cookie
" + cookieName);

So as I investigate this some more...

- in the scripts/selenese, referring to the cookie as drugstore.fish is indeed the
desired behaviour
- drugstore%2Efish says that this is an asp site which [overly] aggressively escapes
things. se-ide sits inside firefox which does not escape the period

and am now thinking about an asp specific hack to deal with this.

right. think i have fixed this. here is the new logic for deletion of a cookie by name
(the name should be the human friendly version (drugstore.fish)

- check that the cookie exists as passed in
- if not, check that the cookie exists using 'standard' encoding rules
- if not, check that the cookie exists using 'standard' encoding rules plus encoding
of _ and . (there could be others that are needed, but those are the two in this bug)

once found the mechanism for 'deleting' is the same.

com.thoughtworks.selenium.SeleniumException: ERROR: Couldn't delete cookie feedType