Troubleshooting a Declaration of WHMCS\View\Menu\Item::setLabel($label) Error

Symptom

After updating to WHMCS 8.4.0, you may observe the following setLabel error:

Whoops\Exception\ErrorException: Declaration of  WHMCS\View\Menu\Item::setLabel($label): Knp\Menu\ItemInterface must be  compatible with Knp\Menu\MenuItem::setLabel(?string $label):  Knp\Menu\ItemInterface in  /var/www/html/billing/vendor/whmcs/whmcs-foundation/lib/View/Menu/Item.php:0
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Solution

Update ionCube® Loader on your server to the newest available stable version.

For help with updating ionCube Loader, contact your hosting provider or system administrator.

HotFix

A hotfix has been created for 8.4.0 only to correct this behavior:

https://whmcs.community/files/file/172-core-17437-client-area-declaration-error-in-setlabel-method/

Workaround

If you cannot update ionCube Loader, you can use the following alternate method:

  1. Download the 8.3.2 Full Release files.
  2. Extract the /vendor/whmcs/whmcs-foundation/lib/View/Menu/Item.php file.
  3. Upload the file to the /vendor/whmcs/whmcs-foundation/lib/View/Menu/ directory, overwriting the current file.

After you have updated ionCube Loader on your server, you can restore the Item.php file from WHMCS 8.4.0.