X-Magento-Tags header containing whitespaces causes exception

[redelschaap]

When the header X-Magento-Tags contains whitespaces, an Zend\Http\Header\Exception\InvalidArgumentException is being thrown when the full page cache is enabled. Block IDs can contain whitespaces due to reformatting in layout XML files, because of the 80 character line length limit.

Preconditions

Using Magento 2.1.2 with nginx and PHP7

Steps to reproduce

1. Have layout files with block_id arguments that contain whitespaces (see image below)
2. Enable full page cache
3. Reload a page

Expected result

The page should be loaded correctly

Actual result

An error Zend\Http\Header\Exception\InvalidArgumentException: Invalid header value detected is being thrown.

Possible fix

Filter out whitespaces within argument tags when reading XML layout files.

Attachment

[ihor-sviziev]

We had a lot issues like this in M1, that were caused by automatic xml formatting in PhpStorm. Would be great to add trim values, it will fix this issue.

[redelschaap]

It would. I couldn't find the right place to add trim functions so quickly, otherwise I would have made a pull request.

[magento-engcom-team]

@redelschaap, thank you for your report.
We've created internal ticket(s) MAGETWO-81249 to track progress on the issue.