Submit results in `AssertionError: Response already started`

[sue.sml2006@…]

This may be an installation issue, but not seeing anything amiss. I followed steps to install the plugin. When i attempt to use the laundry list example, i'm seeing this error:

 Trac detected an internal error:

AssertionError: Response already started

It seems to have taken the update, but what is this error? this was usingtracformsplugin-r8671

Thank you, Sue

[anonymous]

I have the same problem, it started to reproduce after upgrading from TRAC 0.11 to TRAC 0.12.

The issue reproduces when you change values in a form and hit the submit button.

After the error "AssertionError: Response already started", refreshing the page/ticket shows that the new values have been updated in the form.

I have tried TracFormsPlugin 0.2.1 and 0.3 with the same issue.

TRAC 0.11 and TracFormsPlugin 0.2.1 worked ok before the upgrade.

[anonymous]

I can confirm comment comment:1. The same happens on my machine (Trac 0.12). After adding a demo form to a ticket without using [[Include(...)]] (IncludeMacro), I get:

Trac detected an internal error: RuntimeError: No Content-Length header set

When going back to the ticket using the browser history and clicking the update button of the form, the AssertionError occurs.

When I include a template form of a wiki page, I only get the AssertionError.

[Steffen Hoffmann]

a quick fix like what had been done by Mikko Rantalainen for TimeVisualizerPlugin before

[Steffen Hoffmann]

After some research I found, that Trac 0.12 uses stricter HTTP request handling now.

Requiring a valid Content-Length header has been an issue for other plugins before. I recognized this for TimeVisualizerPlugin and later for AutocompleteUsersPlugin (with a different fix).

Please check proposed change​. Hint: notice especially the added length statements in there.

I'll commit that to trunk branch ASAP, provided I'll receive requested privileges.

[Steffen Hoffmann]

Giving higher priority now, because with Trac 0.12 this is a real show-stopper.

Changeset with fix tested and verified is prepared here.

[Steffen Hoffmann]

Ok, got a 'GO' and will do it now.

[Steffen Hoffmann]

(In [9580]) TracFormsPlugin: Adapt to stricter HTTP request handling in Trac >= 0.12, closes #7695.

Fixed RuntimeError: No Content-Length header set similar to work on #7442 done by Mikko Rantalainen for TimeVisualizerPlugin.

[Ryan J Ollos]

Looking at line 55 in the commit, is it not case sensitive to 'Content-type' vs. 'Content-Type' ... or is there something else going on here that I don't understand?

[Steffen Hoffmann]

Replying to rjollos:

Looking at line 55 in the commit, is it not case sensitive to 'Content-type' vs. 'Content-Type' ... or is there something else going on here that I don't understand?

No, certainly not, must have been only me copying from mentioned changeset done by insyte and Mikko. The fix is essentially calculating and adding the missing «Content-Length» header.

I've seen another fix, that doesn't need an explicit calculation, but don't remember now, where to look. I'll announce, if/when I find it, since it looked more elegant to me IIRC.