The Guzzle 7 is complaining about the stream_for method.

[dbclkh]

The Guzzle 7 is complaining about the stream_for method. It is deprecated and they want to use Utils::streamFor instead

[m4olivei]

I picked up a failure in my test suite after this change. I think the change is fine, only you need to reflect it in your dependencies as well. The \GuzzleHttp\Psr7\Utils was introduced in guzzlehttp/psr7:1.7.0. The version constraints on this repo allow guzzlehttp/guzzle:"^6.0 || ^7.0". Guzzle 6 requires guzzlehttp/psr7: ^1.6.1, so in the end if your using Guzzle 6, you could end up with guzzlehttp/psr7:1.6.1 (which was the case for me) and then 💥 errors like this:

Error: Class 'GuzzleHttp\Psr7\Utils' not found

/var/www/html/vendor/kevinrob/guzzle-cache-middleware/src/CacheEntry.php:283
/var/www/html/core/lib/Drupal/Core/Cache/MemoryBackend.php:87
/var/www/html/core/lib/Drupal/Core/Cache/MemoryBackend.php:34
/var/www/html/modules/contrib/guzzle_cache/src/DrupalGuzzleCache.php:86
/var/www/html/modules/*********/src/MpxCacheStrategy.php:78
/var/www/html/vendor/kevinrob/guzzle-cache-middleware/src/Strategy/Delegate/DelegatingCacheStrategy.php:75
/var/www/html/vendor/kevinrob/guzzle-cache-middleware/src/CacheMiddleware.php:142

Note: Stack trace trimmed for brevity.

Ultimately I went back to using version 3.3.1 of kevinrob/guzzle-cache-middleware to fix my issue (since I have no control ATM over Guzzle version in user).

I think guzzlehttp/psr7 should be required here as ^1.7.0 to fix these types of errors on 3.4.

[Kevinrob]

You are right @m4olivei .
I added a constraint in 0e4dfb4 and released a new version v3.4.1