AbanteCart core v.1.4.4 Interface "Psr\Http\Message\StreamInterface" not found

[timlight10]

After updating to 1.4.4, customers cannot complete the checkout process, the fast checkout hangs with a blank screen, or they cannot select a shipping method.

In the error log there is this:

Code Select Expand

2026-05-09 13:49:32 - Unknown Error: AbanteCart core v.1.4.4 Interface "Psr\Http\Message\StreamInterface" not found
Full stack trace:

Code Select Expand

2026-05-09 13:49:32 - Unknown Error: AbanteCart core v.1.4.4 Interface "Psr\Http\Message\StreamInterface" not found
Trace:
#0 /home4/juliann7/public_html/dps/vendor/composer/ClassLoader.php(576): include()
#1 /home4/juliann7/public_html/dps/vendor/composer/ClassLoader.php(427): {closure:Composer\Autoload\ClassLoader::initializeIncludeClosure():575}('/home4/juliann7...')
#2 /home4/juliann7/public_html/dps/extensions/ups/core/ups_sdk/vendor/guzzlehttp/psr7/src/Utils.php(310): Composer\Autoload\ClassLoader->loadClass('GuzzleHttp\\Psr7...')
#3 /home4/juliann7/public_html/dps/extensions/ups/core/ups_sdk/vendor/guzzlehttp/psr7/src/Request.php(57): GuzzleHttp\Psr7\Utils::streamFor('grant_type=clie...')
#4 /home4/juliann7/public_html/dps/extensions/ups/core/ups_sdk/OAuthClientCredentials/src/Request/OAuthClientCredentialsApi.php(384): GuzzleHttp\Psr7\Request->__construct('POST', Object(GuzzleHttp\Psr7\Uri), Array, 'grant_type=clie...')
#5 /home4/juliann7/public_html/dps/extensions/ups/core/ups_sdk/OAuthClientCredentials/src/Request/OAuthClientCredentialsApi.php(122): UPS\OAuthClientCredentials\Request\OAuthClientCredentialsApi->createTokenRequest('client_credenti...', '366R15')
#6 /home4/juliann7/public_html/dps/extensions/ups/core/ups_sdk/OAuthClientCredentials/src/Request/OAuthClientCredentialsApi.php(103): UPS\OAuthClientCredentials\Request\OAuthClientCredentialsApi->createTokenWithHttpInfo('client_credenti...', '366R15')
#7 /home4/juliann7/public_html/dps/extensions/ups/core/utils.php(65): UPS\OAuthClientCredentials\Request\OAuthClientCredentialsApi->createToken('client_credenti...', '366R15')
#8 /home4/juliann7/public_html/dps/extensions/ups/storefront/model/extension/ups.php(366): ups\core\getUPSAccessToken(Object(Registry))
#9 /home4/juliann7/public_html/dps/extensions/ups/storefront/model/extension/ups.php(187): ModelExtensionUps->processRequest(Array, '25', '10', '11', '16')
#10 /home4/juliann7/public_html/dps/storefront/controller/responses/checkout/pay.php(1791): ModelExtensionUps->getQuote(Array)
#11 /home4/juliann7/public_html/dps/storefront/controller/responses/checkout/pay.php(374): ControllerResponsesCheckoutPay->select_shipping(NULL)
#12 /home4/juliann7/public_html/dps/core/engine/dispatcher.php(306): ControllerResponsesCheckoutPay->main()
#13 /home4/juliann7/public_html/dps/core/engine/response.php(87): ADispatcher->dispatch()
#14 /home4/juliann7/public_html/dps/core/engine/router.php(222): ATypeResponse->build('checkout/pay')
#15 /home4/juliann7/public_html/dps/core/engine/router.php(86): ARouter->route()
#16 /home4/juliann7/public_html/dps/index.php(82): ARouter->processRoute('r/checkout/pay')
#17 {main} in /home4/juliann7/public_html/dps/extensions/ups/core/ups_sdk/vendor/guzzlehttp/psr7/src/Stream.php on line 12
Any advise?

[timlight10]

I have disabled and uninstalled the default UPS extension for now, and customers can now complete orders using FedEx instead. Would like to get default UPS working again though!

[Basara]

Hello.
We tested an upgrade from 1.4.3 to 1.4.4, and UPS is working correctly in that case.

This error points to a missing dependency/class file from the UPS SDK rather than a general checkout issue.

Please compare your installed UPS extension files with the current 1.4.4 master UPS files here:

https://github.com/abantecart/abantecart-src/tree/master/public_html/extensions/ups

Pay special attention to the extensions/ups/core/ups_sdk/vendor/ directory and make sure all files are present and uploaded correctly. Also check file and folder permissions so PHP can read these files.

Another possibility is hosting-side security filtering. If your host has an internal firewall, for example ModSecurity, it may block part of the new UPS code or its requests. You may need to ask the hosting provider to check the ModSecurity/firewall logs for blocked requests related to the UPS extension.