How did I upgrade frugue.com from Magento 2.1.9 to 2.3.0?

Administration Upgrade
1

Step 1

sudo composer self-update

Step 2

Replace the require-dev section of the root’s composer.json file with the code from Magento 2.2.7:

"require-dev": {
	"phpunit/phpunit": "~6.2.0",
	"squizlabs/php_codesniffer": "3.2.2",
	"magento/magento2-functional-testing-framework": "2.3.8",
	"phpmd/phpmd": "@stable",
	"pdepend/pdepend": "2.5.2",
	"friendsofphp/php-cs-fixer": "~2.2.1",
	"lusitanian/oauth": "~0.8.10",
	"sebastian/phpcpd": "2.0.4"
},

Step 3

Replace the autoload/psr-0 section of the root’s composer.json file with the code from Magento 2.2.7:

"psr-0": {
	"": [
		"app/code/",
		"generated/code/"
	]
},

Step 4

Add the the autoload/psr-0/exclude-from-classmap section to the root’s composer.json file (with the value from from Magento 2.2.7):

"exclude-from-classmap": [
	"**/dev/**",
	"**/update/**",
	"**/Test/**"
]

Step 5

Upgrade PHP from 7.0.x to 7.1.x.

Step 6

rm -rf composer.lock

Step 7

composer require magento/product-community-edition:2.2.7

Step 8

Replace the update folder with the same folder from the Magento 2.2.7 distributive.

Step 9

bin/magento setup:upgrade

Step 10

bin/magento setup:static-content:deploy -f en_US de_DE fr_FR --area frontend --theme TemplateMonster/theme007 && bin/magento setup:static-content:deploy -f en_US --area adminhtml --theme Magento/backend

Step 11

bin/magento indexer:reindex && bin/magento cron:run && bin/magento cache:clean

Step 12

Replace the require-dev section of the root’s composer.json file with the code from Magento 2.3.0:

Step 13

Replace the config section of the root’s composer.json file with the code from Magento 2.3.0:

Step 14

Add the conflict section to the root’s composer.json file:

Step 15

Replace the autoload/psr-4 section of the root’s composer.json file with the code from Magento 2.3.0:

Step 16

rm -rf vendor/composer/installed.json
find . -name "composer.lock" -type f -delete

Step 17

composer require magento/product-community-edition:2.3.0

Step 18

Upgrade PHP from 7.1.x to 7.2.x.

Step 19

UPDATE core_config_data  SET value = 470 WHERE path = 'theme_options/category_page/grid_view/image_width';

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