Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.
Problem 1
The requested package php-http/guzzle6-adapter ^1.2@dev exists as php-http/guzzle6-adapter[dev-clarify-guzzle-argument, dev-master, 2.x-dev, v0.1.0, v0.2.0, v0.2.1, v0.3.0, v0.3.1, v0.4.0, v0.4.1, v1.0.0, v1.1.0, v1.1.1, v2.0.0, v2.0.1] but these are rejected by your constraint.
Problem 2
swiftmailer/swiftmailer v6.1.3 requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
swiftmailer/swiftmailer v6.1.2 requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
swiftmailer/swiftmailer v6.1.1 requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
swiftmailer/swiftmailer v6.1.0 requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
swiftmailer/swiftmailer v6.0.2 requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
swiftmailer/swiftmailer v6.0.1 requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
swiftmailer/swiftmailer v6.0.0 requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
swiftmailer/swiftmailer 6.2.x-dev requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
Installation request for yiisoft/yii2-swiftmailer dev-master -> satisfiable by yiisoft/yii2-swiftmailer[dev-master].
Running update with --no-dev does not mean require-dev is ignored, it just means the packages will not be installed. If dev requirements are blocking the update you have to resolve those problems.
composer install:
Loading composer repositories with package information
Installing dependencies from lock file
Warning: The lock file is not up to date with the latest changes in composer.json. You may be getting outdated dependencies. Run update to update them.
Your requirements could not be resolved to an installable set of packages.
Problem 1
Installation request for doctrine/inflector 1.3.x-dev -> satisfiable by doctrine/inflector[1.3.x-dev].
doctrine/inflector 1.3.x-dev requires php ^7.1 -> your PHP version (5.6.40) does not satisfy that requirement.
Problem 2
Installation request for doctrine/inflector dev-master -> satisfiable by doctrine/inflector[dev-master].
doctrine/inflector dev-master requires php ^7.1 -> your PHP version (5.6.40) does not satisfy that requirement.
Problem 3
Installation request for swiftmailer/swiftmailer 6.1.x-dev -> satisfiable by swiftmailer/swiftmailer[6.1.x-dev].
swiftmailer/swiftmailer 6.1.x-dev requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
Problem 4
Installation request for swiftmailer/swiftmailer dev-master -> satisfiable by swiftmailer/swiftmailer[dev-master].
swiftmailer/swiftmailer dev-master requires php >=7.0.0 -> your PHP version (5.6.40) does not satisfy that requirement.
Problem 5
doctrine/inflector 1.3.x-dev requires php ^7.1 -> your PHP version (5.6.40) does not satisfy that requirement.
knplabs/packagist-api dev-master requires doctrine/inflector ~1.0 -> satisfiable by doctrine/inflector[1.3.x-dev].
Installation request for knplabs/packagist-api dev-master -> satisfiable by knplabs/packagist-api[dev-master].
composer.json:
composer update:
Loading composer repositories with package information Updating dependencies Your requirements could not be resolved to an installable set of packages.
Problem 1
Running update with --no-dev does not mean require-dev is ignored, it just means the packages will not be installed. If dev requirements are blocking the update you have to resolve those problems.
composer install:
Loading composer repositories with package information Installing dependencies from lock file Warning: The lock file is not up to date with the latest changes in composer.json. You may be getting outdated dependencies. Run update to update them. Your requirements could not be resolved to an installable set of packages.
Problem 1