I have been seeing “setting a property that has only a getter error” poping up in my firebug for a while, which I believed was a Firefox extension conflict with new version of firebug.

A recent post to dojo-interest mailing list caught my eye: basically, a user can reproduce this problem by just loading dojo from google CDN.

I decided to take a look at this and try to figure out why.

A firebug bug report is filed about this error: with FireFox>3.5.2, modifying window.console (or attributes on console) would trigger this error. However, in the test case mentioned in the post, even if dojo is not loaded, the error still pops up in firebug, so it must be in some firefox extension, rather than dojo.

The only other extension I have in my development firefox profile is Selenium-IDE 1.0.4. Disabling it, and the error immediately goes away. Searching selenium-ide bug report, it turns out it has just been fixed in Selenium-IDE 1.0.5 (direct link to the xpi file).

In a summary, if you are getting “setting a property that has only a getter error” Error in FF 3.6 with any page, make sure you have at least Selenium-IDE 1.0.5. If you don’t use it, then you are probably messing around with window.console. (the error message would be much more helpful if it states what property is being accessed)