Undefined array key "content-type" in /vendor/quickbooks/v3-php-sdk/src/Core/HttpClients/SyncRestHandler.php:281

[craiglondon]

I am using v6.2.0. The first occurrence of this error happened in my application on 07/26/2025 12:07 AM EST.

/vendor/quickbooks/v3-php-sdk/src/Core/HttpClients/SyncRestHandler.php:281
Stack trace:
#0
/vendor/quickbooks/v3-php-sdk/src/Core/HttpClients/SyncRestHandler.php(281):
yii\base\ErrorHandler->handleError()
#1
/vendor/quickbooks/v3-php-sdk/src/Core/HttpClients/SyncRestHandler.php(217):
QuickBooksOnline\API\Core\HttpClients\SyncRestHandler->LogAPIResponseToLog()
#2
/vendor/quickbooks/v3-php-sdk/src/Core/HttpClients/SyncRestHandler.php(127):
QuickBooksOnline\API\Core\HttpClients\SyncRestHandler->OAuth2APICall()
#3
/vendor/quickbooks/v3-php-sdk/src/DataService/DataService.php(1018):
QuickBooksOnline\API\Core\HttpClients\SyncRestHandler->sendRequest()
#4
/modules/v1/components/postbacks/QuickBooks.php(358):
QuickBooksOnline\API\DataService\DataService->Query()```

[GautamParmar22]

I encountered the same issue using v6.2.0 — LogAPIResponseToLog() was throwing a "Content-Type on null" and null comparison error whenever the API response didn’t include a Content-Type header.

The error originated from:

/vendor/quickbooks/v3-php-sdk/src/Core/HttpClients/SyncRestHandler.php:281

I submitted a fix in PR #559
, which adds an isset() check before accessing the Content-Type header.

This ensures that XML parsing is only attempted when the header exists, preventing runtime errors and making the logging process more reliable.