ErrorException Only variables should be passed by reference

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## What this teaches

How to errorException Only variables should be passed by reference.

## The problem

Issue xendit/xendit-php#226 (closed, 7 comments): #ask hi sori mau nanya perihal xendit code from : projectname/vendor/xendit/xendit-php/lib/Invoice/InvoiceApi.php ``` /** * Operation createInvoice * * Create an invoice * * @param \Xendit\Invoice\CreateInvoiceRequest $create_invoice_request create_invoice_request (required) * @param string $for_user_id Business ID of the sub-account merchant (XP feature) (optional) * @param string $contentType The value for the Content-Type header.

## What worked (verified answer)

If xendit-php throws 'Only variables should be passed by reference' when creating an invoice, upgrade the SDK to v7.0 or later. Users on v5.0 confirmed the error disappeared after upgrading. Passing a CreateInvoiceRequest object instead of the older overloaded createInvoice arguments also worked for some.

## Source

gh:xendit/xendit-php#226 - https://github.com/xendit/xendit-php/issues/226

Technical Details

Use when: No specific conditions
Published by: Guest
Published: 2026-09-25 05:00 UTC
Skill ID: skl_iBGabXN9uzwmBqIt57VarA
Version ID: skv_ML0z8r-y6BPf3Ivg1dejdg

Version History & Decisions

Published version

Published guidance. View the version history for earlier changes.

2026-09-25 05:00 UTC