Call to undefined method mb_str_split()

wp-Typography author here: One solution would be to upgrade your PHP to 7.4, alleviating the polyfill for mb_str_split (please not that wp-Typography does not include the polyfill library in question, but rather looks whether mb_str_split exists before trying to use it).

I’ve noticed the same issue with another plugin, but I don’t know why the mbstring polyfill fails.

wow, thanks for the quick reply. How did you see it so fast (since I did not post in the wp typography board)?

I just checked with my hosting provider and it seems I can only upgrade to PHP 7.3 right now. Would that be enough already or does it have to be PHP 7.4?

You can subscribe to keywords ??

As for PHP, upgrading to 7.3 is worthwhile per se, but it won’t help with this particular issue as mb_str_split has only been added in 7.4.

I see. That makes sense then. I will have to wait until my provider offers an upgrade to PHP 7.4 then. Thanks!

Ah, I haven’t checked, but I think the issue might be that there are two plugins with the library in question (one with an older version), just not wp-Typography. If you search for the directory name “polyfill-mbstring”, you should find the other one.

but then, what do I do?
I know that the conflicting plugin is WPForms Lite. That’s why I posted it here. I also just checked it and saw that there is indeed a “polyfill-mbstring” folder inside the structure of the WPForms Lite plugin.

• This reply was modified 4 years, 4 months ago by Beta2k.

Ah, you are right, the older version seems to be in this plugin, yes. Using common Composer libraries (like this) without “scoping” them is not a good idea, as conflicts are bound to happen. Unfortunately the only solution is to do what you did, nudging plugin authors to fix their code.

so an upgrade to PHP 7.4 also won’t help?

No, that will help fix the specific error. But the underlying problem (bundled old library versions) will remain and could cause different issues in the future.

argl. that’s a mess then. thanks though.

Hi @beta2k,

Thanks for reaching out!

In the current polyfill-mbstring library version (1.17) in WPForms Lite, we’ve included the method mb_str_split(), which was referenced in the error message you’ve shared.

In the next update to WPForms Lite, we’ll be updating the polyfill-mbstring library to its current version (1.18) also.

I’ve tried activating both WPForms Lite and wp-Typography on sites running PHP 5.6.39 and 7.3.5, and they did not seem to show any errors.

If you’ve more details on how we can replicate the issue, please let us know so we can investigate further.

Thanks!

@beta2k: I got confused reading the error log, it’s should have been obvious that WPForms is not the plugin containing the old library version (because its bootstrap file does contain the polyfill, so the old class implementation has to come from somewhere else). Please have a look through your plugins to find the culprit and ask them to update and scope their libraries.

@ethanchoi: If you use Composer in WordPress plugins, it is best to use a tool like PHP-Scoper for re-scoping all libraries to prevent errors like the one described in this thread. You can look at my plugins (e.g. wp-Typography) for a possible implementation (its not complete “plug-and-play”, but you probably have a build process already, so adding one additional step should not be too bad).

@pputzer, thanks for your reply. I didn’t check again, yet, but have a question: how is it possible then, that the problem only arises, if I have wp-typography and wpforms-lite activated at the same time? If I disable one of them, the problem is gone.

@beta2k WPForms has one library, containing the function (which internally is implemented by a class method). Another plugin contains an older version of the same library, where the implementation class does not contain the called method. By coincidence, the second plugin loaded before WPForms, which means that its class definition is used. The stub definition for the mb_str_split function is still loaded from WPForms, though.

wp-Typography checks for the existence of the function – it does exist because WPForms has it. When it is called, though, the implementation class loaded from the second plugin does not have the called method, thus the error.

Disabling WPForms removes the function stub, which means wp-Typography will use its own implementation instead. Disabling wp-Typography will remove the call to the function, thus never triggering the error because the other mbstring polyfills have not changed (much) in a long time. (mb_str_split is a PHP 7.4 addition.)