importWxr step encountering fatal PHP error with function redeclaration

[brandonpayton]

Prerequisites

• I have carried out troubleshooting steps and I believe I have found a bug.
• I have searched for similar bugs in both open and closed issues and cannot find a duplicate.

Describe the bug

The importWxr step is encountering a fatal PHP error when running @bph's blueprint from
https://github.com/wptrainingteam/hellodashboard

[17-Oct-2025 01:38:09 UTC] PHP Fatal error:  Cannot redeclare normalizer_is_normalized() in /wordpress/wp-content/plugins/wordpress-importer/php-toolkit/DataLiberation/vendor-patched/symfony/polyfill-intl-normalizer/bootstrap.php on line 19

The error is a bit strange because the redeclaration error occurs right after a function_exists() check for the same function:

Expected behavior

Import completes without a fatal error.

Actual behavior

The import fails with a fatal error.

Steps to reproduce

@bph may adjust the blueprint in that repo to work around the issue while we are fixing this one, so I've copied the Blueprint to a Gist for repro:
https://gist.githubusercontent.com/brandonpayton/e08e513901f2e8845816b1855e611da6/raw/256663a30c52a0e55430f91529f4465de097fd2c/gistfile1.txt

Here is a Playground link for repro:
https://playground.wordpress.net/?blueprint-url=https%3A%2F%2Fgist.githubusercontent.com%2Fbrandonpayton%2Fe08e513901f2e8845816b1855e611da6%2Fraw%2F256663a30c52a0e55430f91529f4465de097fd2c%2Fgistfile1.txt

Isolating the problem

• I have deactivated other plugins and confirmed this bug occurs when only this plugin is active.
• This bug happens with a default WordPress theme active.
• I can reproduce this bug consistently using the steps above.

[brandonpayton]

Note:
Based on my tests, if the Blueprint is adjusted to use an 8.x version of PHP, the error goes away.

I don't currently recall the state of dynamic Intl support for Playground web. @mho22 and @adamziel, based on your knowledge, do you have any ideas about this one?

[bph]

Thanks @brandonpayton for creating the issue, conduct some research and help me with a workaround.
I updated the blueprint.json with the PHP version of 8.3 and it loads successfully.

[adamziel]

It’s one of disabled_functions in php.ini when icu.dat isn’t loaded, and PHP implementation of disabled_functions is really weird. We’re almost there with dynamic extensions, the last problem is not inflating php.wasm by another 8MB when supporting dynamic extensions. See #2591.