Delete all visible cookies throws an exception

I am using selenium with a python client. When you do selenium.delete_all_visible_cookies I get an exception:

ERROR: Command execution failed. Please find the forum at http://clearspace.openqa.org for error details from the log window. error message: Invalid URI Sequence

Log window error:

error(1254427481456): Exception details: 
message -> malformed URI sequence, 
fileName -> http://localhost:4444/selenium-server/core/scripts/selenium-browserbot.js,
lineNumber -> 1169, 
stack -> 
("WSS_GW",[object HTMLDocument])@http://localhost:4444/selenium-server/core/scripts/selenium-browserbot.js:1169 
("WSS_GW",".mysite","/",[object HTMLDocument])@http://localhost:4444/selenium-server/core/scripts/selenium-browserbot.js:1208 
("WSS_GW",".mysite","/",[object HTMLDocument])@http://localhost:4444/selenium-server/core/scripts/selenium-browserbot.js:1213 
("WSS_GW",".mysite","/",[object HTMLDocument])@http://localhost:4444/selenium-server/core/scripts/selenium-browserbot.js:1236 
("WSS_GW","mysite","/",[object XPCCrossOriginWrapper])@http://localhost:4444/selenium-server/core/scripts/selenium-browserbot.js:1248 
("","")@http://localhost:4444/selenium-server/core/scripts/selenium-api.js:2607
("","")@http://localhost:4444/selenium-server/core/scripts/htmlutils.js:60 
([object Object],[object Object])@http://localhost:4444/selenium-server/core/scripts/selenium-commandhandlers.js:310 
()@http://localhost:4444/selenium-server/core/scripts/selenium-executionloop.js:112 
(-10)@http://localhost:4444/selenium-server/core/scripts/selenium-executionloop.js:78 
(-10)@http://localhost:4444/selenium-server/core/scripts/htmlutils.js:60 , 
name -> URIError

      

        
        
        
      

    

Any idea what's going on?