Heroku Class 'NumberFormatter' not found

Question

Deploying my Laravel 7 app in Heroku I get this error, it appears only in Heroku, not on my local box (localhost)

Class 'NumberFormatter' not found (View: ...)

Server Details:

• Heroku
• PHP 7.4.12
• Laravel Framework 7.30.4

Answer 1

The NumberFormatter class^Docs requires the PHP Internationalization extension (intl)^Docs, and this extension is not available built-in on Heroku Heroku Built-in Extensions^{Heroku Docs}.

Instead Heroku gives you permission to use optional extensions^{Heroku Docs}.

To make use of them you can either use the composer command to require it ("ext-intl"):

composer require ext-intl

Or you can manually add this to composer.json in the require section^{Composer Docs}:

{
  "require": {
    "ext-intl": "*"
  }
}

Commit the file and push the changes to Heroku. The error should be gone until you find the next missing class.

This is another example, why it is a good idea if you have a Composer based PHP project, to document the extensions in use as well in the composer.json file.

When the day comes, you have them documented in the Composer JSON already.

And systems like Heroku can benefit from it, too!