Opened on 07/04/2016 at 12:34:00 PM
Closed on 07/06/2016 at 05:12:37 PM
Last modified on 07/02/2019 at 11:48:48 AM
#4227 closed defect (fixed)
NS_ERROR_ILLEGAL_VALUE on startup (element hiding)
| Reported by: | trev | Assignee: | trev |
|---|---|---|---|
| Priority: | P1 | Milestone: | Adblock-Plus-2.8-for-Firefox |
| Module: | Adblock-Plus-for-Firefox | Keywords: | |
| Cc: | mapx | Blocked By: | |
| Blocking: | #521 | Platform: | Unknown / Cross platform |
| Ready: | yes | Confidential: | no |
| Tester: | Ross | Verified working: | yes |
| Review URL(s): | |||
Description (last modified by trev)
Environment
Firefox 50.0a1 nightly, Adblock Plus 2.7.3.4186
How to reproduce
- Start Firefox
- Press Ctrl/Cmd-Shift-J to open the Browser Console.
Observed behaviour
Error message coming from elemHide.js line 346:
NS_ERROR_ILLEGAL_VALUE: Component returned failure code: 0x80070057 (NS_ERROR_ILLEGAL_VALUE) [nsIDOMWindowUtils.addSheet]
Expected behaviour
No error messages.
Background
The error is caused by us trying to add the stylesheet twice in some cases.
What to change
Keeping track of documents we dealt with already would create unnecessary overhead. It's better to catch NS_ERROR_ILLEGAL_VALUE and ignore it now that we understand the background of this error.
Attachments (0)
Change History (7)
comment:1 Changed on 07/04/2016 at 01:41:03 PM by trev
comment:2 Changed on 07/06/2016 at 12:39:49 PM by trev
I was able to establish that this is unrelated to the stylesheet, the issue is rather the window we try to add it to. Consequently, this error pops up whenever a new browser window is opened, not merely at startup. Not sure yet what kind of windows this affects, it does affect extension windows however like the ones loaded inside a Web Extensions pop-up.
comment:3 Changed on 07/06/2016 at 01:35:51 PM by trev
- Description modified (diff)
- Owner set to trev
Just great: NS_ERROR_INVALID_ARG and NS_ERROR_ILLEGAL_VALUE are the same thing. This explains how this code can return NS_ERROR_ILLEGAL_VALUE, and it's also fairly easy to see where it comes from. In fact, "content-document-global-created" observer is triggered twice for some documents - and addSheet() will throw NS_ERROR_ILLEGAL_VALUE if you try to re-add a stylesheet.
comment:4 Changed on 07/06/2016 at 01:47:32 PM by trev
- Review URL(s) modified (diff)
- Status changed from new to reviewing
comment:5 Changed on 07/06/2016 at 05:10:57 PM by abpbot
A commit referencing this issue has landed:
Issue 4227 - Add some checks to consider edge conditions when element hiding stylesheet is applied
comment:6 Changed on 07/06/2016 at 05:12:37 PM by trev
- Milestone set to Adblock-Plus-for-Firefox-next
- Resolution set to fixed
- Status changed from reviewing to closed
comment:7 Changed on 09/07/2016 at 11:07:54 AM by Ross
- Tester changed from Unknown to Ross
- Verified working set
Looks fixed / Could not reproduce.
ABP 2.7.3.4198-beta
Nightly 51.0a1 / Windows 7
Firefox 48 / Windows 7
It seems that for some reason the stylesheet isn't ready to be used immediately on startup. However, I cannot see any codepath that would return NS_ERROR_ILLEGAL_VALUE: nsDOMWindowUtils::AddSheet itself can only return NS_ERROR_INVALID_POINTER, NS_ERROR_INVALID_ARG and NS_ERROR_FAILURE. It calls into nsDocument::AddAdditionalStyleSheet at the end but that one cannot return anything but NS_ERROR_INVALID_ARG and NS_OK. I suspect that the error code is actually coming from some security wrapper which is supposed to be transparent to us.