Regression: class-wp-rest-server.php

[perrelet]

In ​https://github.com/WordPress/WordPress/commit/3f1e6a6a5031b319fd5ebfaaf6598fec3fe78fb1

The rest_send_nocache_headers block is moved after rest_pre_serve_request.

However this renders rest_pre_serve_request useless because rest_send_nocache_headers sends / removes http headers. As a result, using rest_pre_serve_request for it's intended purpose (to manually send the request) results in Cannot modify header information - headers already sent.

Suggest moving the rest_send_nocache_headers block before the rest_pre_serve_request filter.

The rest_send_nocache_headers block was moved after rest_pre_serve_request in ​https://github.com/WordPress/WordPress/commit/3f1e6a6a5031b319fd5ebfaaf6598fec3fe78fb1.

This renders rest_pre_serve_request useless because rest_send_nocache_headers sends / removes http headers. As a result, using rest_pre_serve_request for it's intended purpose (to manually send the request) results in:

Cannot modify header information - headers already sent.

Suggest moving the rest_send_nocache_headers block before the rest_pre_serve_request filter.

Trac ticket: https://core.trac.wordpress.org/ticket/59722#ticket

[SergeyBiryukov]

Hi there, welcome back to WordPress Trac! Thanks for the report.

Introduced in [56834], moving to the milestone to get more eyes on this.

[hellofromTonya]

Moving up the priority for tracking and awareness.

[perrelet]

Thank you @SergeyBiryukov & @hellofromTonya 🙏

[jorbin]

In 57012:

REST API: Move rest_pre_serve_request filter to after no cache headers are sent.

[56834] adjusted the order of activity inside the rest server responses. This lead to the rest_pre_serve_request filter potentially blocking the sending of the no cache headers. This moves that action back to being after the sending of no cache headers has finished to restore the pre 6.3.2 order of these two actions.

Props perrelet, SergeyBiryukov, peterwilsoncc.
Fixes #59722.

[jorbin]

Thank you @perrelet for identifying this.

Reopening for 2nd committer sign-off to backport to both the 6.4 and 6.3 branches.

[hellofromTonya]

[57012] LGTM for backport to 6.4

[hellofromTonya]

Whoops, sorry Jorbin, I missed that it's also for 6.3. +1 for that backport too.

[jorbin]

In 57014:

REST API: Move rest_pre_serve_request filter to after no cache headers are sent.

Merges [57012] to 6.4 branch.

[56834] adjusted the order of activity inside the rest server responses. This lead to the rest_pre_serve_request filter potentially blocking the sending of the no cache headers. This moves that action back to being after the sending of no cache headers has finished to restore the pre 6.3.2 order of these two actions.

Props perrelet, SergeyBiryukov, peterwilsoncc, hellofromTonya.
Fixes #59722.

[jorbin]

In 57015:

REST API: Move rest_pre_serve_request filter to after no cache headers are sent.

Merges [57012] to 6.3 branch.

[56834] adjusted the order of activity inside the rest server responses. This lead to the rest_pre_serve_request filter potentially blocking the sending of the no cache headers. This moves that action back to being after the sending of no cache headers has finished to restore the pre 6.3.2 order of these two actions.

Props perrelet, SergeyBiryukov, peterwilsoncc, hellofromTonya.
Fixes #59722.

[jorbin]

Thanks everyone. As 6.3 is still being maintained, I wanted to include the fix there as well if/when a 6.3.3 is released but most likely this fix will come in 6.4.