I was trying to track this issue down together with @Lisawinegar when she came up with it on IRC yesterday. To quote her, she used "OS X El Capitan and i'm in safari v10,0" and experienced the issue from MobileFrontend wikitext (not visual) edit page¹. When we tried to reproduce this, we were unable to do so - tested all four combinations of wikitext/VE and MobileFrontend/Desktop, it even worked out for her on the very same page (MobileFrontend wikitext) she had tried in the first place, as proven by a test edit with Tag: Mobile web edit on that page. I couldn't reproduce this in any way either, so we agreed it must have been transient and didn't file a bug, until this came up again at some other place today as described in the task.

¹ Don't get confused by that browser information and the usage of MobileFrontend - she used a link that was sent to her, resulting in using the mobile page on desktop.

And another user: https://en.wikipedia.org/wiki/User_talk:Swisshill#Error_message

I'm having the same problem with a user in -help today.

The user reports trying to create the page "Paula Klien" using a manual translation of the text from the pt.wiki results in the "empty server response" error. Their page creation trips numerous edit filters (https://en.wikipedia.org/w/index.php?title=Special:AbuseLog&wpSearchUser=Pkartwoman) but examining each edit filter reveals that they're all empty (new size, old size and edit size change are all 0 bytes).

They also report disabling VisualEditor does not resolve the situation.

This was also reported in OTRS ticket #2017050110007352; I've requested further details.

See also the reports here: https://en.wikipedia.org/wiki/Wikipedia:VisualEditor/Feedback#Error_saving_data_to_server:_Empty_server_response

Wiki Ed has been getting a lot of messages from instructors and student editors over the weekend, continuing through today. Seems to be hitting en-wiki pretty hard. @Jdforrester-WMF is this VE-specific?

Another report here, might be related to saving link additions? https://en.wikipedia.org/wiki/Wikipedia:Teahouse#Error_when_I_try_to_post

In T164157#3225789, @Ragesoss wrote:

is this VE-specific?

Given that we have no clue were this comes from, the best thing to look for is probably the error message. In a nearly pure vagrant mw folder, role visualeditor enabled:

eddie@eddie-pc:~/develop/mediawiki/mediawiki$ grep -nre "Empty server response"
extensions/VisualEditor/modules/ve-mw/init/ve.init.mw.ArticleTarget.js:731:     this.showSaveError( ve.msg( 'visualeditor-saveerror', 'Empty server response' ), false /* prevents reapply */ );

So as this message is not to be found anywhere in core but only in extensions/VisualEditor and given that all screenshots I've seen so far show the VE, all reports either mention the VE or don't mention anything about which editor was used, chances are that it is VE-specific.

As I'm counting six reports plus a unknown number of

In T164157#3225789, @Ragesoss wrote: Wiki Ed has been getting a lot of messages

and given that even if we find a fix, we won't be able to deploy it until Monday, we should send out a notice about this IMHO.

I've recieved this error as well, using 2 different computers, both windows. What is interesting is that I also get a similar error when previewing source editing: Error loading data from server: Failed to connect. I have a perfect connection and other websites load fine which would give me reason to believe that this is a server-sided error

One instructor reported that "many of them are receiving" the empty server response error message, there are at least two other reports of the same error from other users that Wiki Ed received.

From what I can tell, it seems to be intermittent; I think at least some users were able to edit successfully later, after failing initially. I just made a few edits to pages that I think one user was having trouble with.

In T164157#3224945, @Nick wrote:

They also report disabling VisualEditor does not resolve the situation.

In T164157#3225980, @Rowanharley wrote:

What is interesting is that I also get a similar error when previewing source editing: Error loading data from server: Failed to connect.

Both of you, can you tell what "source editor" was actually used? We do have the plain old wikitext editor in core but also a newer version that is part of the VisualEditor extension. @Rowanharley Your report and error message suggest that you've experienced the issue with the former. If that is really the case, we indeed can drop the idea of searching the issue in VisualEditor and have to look on the API used for previewing & saving edits in core, that both "plain old Core-Editor" and VE use. I'm going to have a look for that other error message.

@EddieGP

I've not been able to speak to the user who was encountering issues, I would treat their assertion that they disabled VisualEditor fully with a pinch of salt. I did have a report this morning of the same issue (so can confirm it's still occurring, as I write this).

I switched to my non-admin account, enabled VisualEditor, and was able to recreate the error. I enabled the Beta 2017 Wikitext editor and was also able to recreate the error. Checking in the Console, I'm getting just the one error.

Failed to set referrer policy: The value 'origin-when-cross-origin' is not one of 'no-referrer', 'origin', 'no-referrer-when-downgrade', or 'unsafe-url'. Defaulting to 'no-referrer'.

Disabling VisualEditor and using the 'proper' source editor (rather than the VisualEditor extension) to make the exact same edit resulted in no such error, and the edit saved correctly (https://en.wikipedia.org/w/index.php?title=Draft:Impossible_(magic_show)&diff=prev&oldid=778310034)

I think this might be CAPTCHA related. When I try making an edit on an unconfirmed account that adds links (that in the normal text editor would require CAPTCHA), I get this error message. Will test further.

EDIT: Did some further testing and quite confident this is the issue. I only get the error when adding a link that requires CAPTCHA; adding a wikipedia URL doesn't require captcha and doesn't give me the error, but other links do. This is consistent with the posts reported above too ("I can successfully post changes if I don't include a citation to a news article", and Nick's test edit which didn't save from his non-confirmed account).

Also reported on de.wiki and mediawiki.org.

Added the 2017WE tag because it may be related.

Reported on fr.wp. People managed to avoid this message when they weren't using a specific reference. I'm waiting for clarifications.

This definitely sounds like an issue with displaying CAPTCHA in VE.

All changes in ConfirmEdit that went out in wmf.21:

• 37f2dcfd23364de9e2a717dfd229e9d3bd668838 (variable rename; followed-up in a480d98b3f2664d97004a5def88b06abd93039c5)
• 67a909fd8abac9e133046f37a0587a4cd9b14750 (test-only)

Neither of those look like they'd have caused this.

All changes to VE's init/integration that went out in wmf.21:

• 371ac353cff5353db34009a87d46056875afdab3 (essentially just an i18n change, didn't touch the save API code)
• 91a75e3fefc04f71357d2d9b16b0ac0a8aa7e7e5 (limited retries to once for badToken errors only)
• d989de5c09983295fd880de9afae0a72cf11ba1e (code simplification, didn't touch the save API code)
• 21bd2a5b186a23805cb885075eccc244c73ddafe (better support for IE6, didn't touch the save API code)
• e7f430e5a0b49da385a4d3794217520a31fb5452 (better support for read-only wiki mode, didn't touch the save API code)

I'm perplexed.

@Jdforrester-WMF

Please don't ever do this again for urgent tasks. By claiming the task you hid it from my triage process

I'm sorry that this doesn't conform with your teams practices and of course won't do so again. That said, your comment doesn't sound friendly to me and I don't really buy the "and delayed us fixing it" part, given that this task is open since Saturday and your comment comes in not even three hours after me grabbing that task. I won't blame you for not noticing this for two and a half days (especially as it was created on the weekend), so please don't blame me in a comment you're posting less than three hours after me grabbing that task. All I've done was trying to help. Thanks.

Change 351324 had a related patch set uploaded (by Jforrester; owner: Jforrester):
[mediawiki/extensions/VisualEditor@master] Follow-up 91a75e3fe: Respect the new signature for saveFail() everywhere

https://gerrit.wikimedia.org/r/351324

In T164157#3228083, @Jdforrester-WMF wrote:

• 91a75e3fefc04f71357d2d9b16b0ac0a8aa7e7e5 (limited retries to once for badToken errors only)

This was the one; it failed to adjust the code for non-badToken save failures.

Change 351326 had a related patch set uploaded (by Esanders; owner: Esanders):
[mediawiki/extensions/VisualEditor@master] Follow-up I488fd7e74: Adjust saveFail calls for new function signature

https://gerrit.wikimedia.org/r/351326

Change 351324 abandoned by Jforrester:
Follow-up 91a75e3fe: Respect the new signature for saveFail() everywhere

Reason:
Let's do Ed's then.

https://gerrit.wikimedia.org/r/351324

Change 351326 merged by jenkins-bot:
[mediawiki/extensions/VisualEditor@master] Follow-up I488fd7e74: Adjust saveFail calls for new function signature

https://gerrit.wikimedia.org/r/351326

Change 351329 had a related patch set uploaded (by Jforrester; owner: Esanders):
[mediawiki/extensions/VisualEditor@wmf/1.29.0-wmf.21] Follow-up I488fd7e74: Adjust saveFail calls for new function signature

https://gerrit.wikimedia.org/r/351329

In reply to T164157#3228051 by @Jdforrester-WMF:

@Jdforrester-WMF: If non-team members working on important bugs creates an issue then your triage process is broken and something you should fix.

Change 351329 merged by jenkins-bot:
[mediawiki/extensions/VisualEditor@wmf/1.29.0-wmf.21] Follow-up I488fd7e74: Adjust saveFail calls for new function signature

https://gerrit.wikimedia.org/r/351329

Mentioned in SAL (#wikimedia-operations) [2017-05-02T17:05:20Z] <catrope@naos> Synchronized php-1.29.0-wmf.21/extensions/VisualEditor/modules/ve-mw/init/ve.init.mw.ArticleTarget.js: T164157 (duration: 01m 00s)

My fault. Sorry :(

Change 388753 had a related patch set uploaded (by MacFan4000; owner: Esanders):
[mediawiki/extensions/VisualEditor@REL1_29] Follow-up I488fd7e74: Adjust saveFail calls for new function signature

https://gerrit.wikimedia.org/r/388753

Change 388753 merged by jenkins-bot:
[mediawiki/extensions/VisualEditor@REL1_29] Follow-up I488fd7e74: Adjust saveFail calls for new function signature

https://gerrit.wikimedia.org/r/388753