Magento 2.2.5 to 2.3 upgrade error

Question

added:

"autoload": {
"psr-4": {
  "Magento\\Framework\\": "lib/internal/Magento/Framework/",
  "Magento\\Setup\\": "setup/src/Magento/Setup/",
  "Magento\\": "app/code/Magento/",
  "Zend\\Mvc\\Controller\\": "setup/src/Zend/Mvc/Controller/"
},

composer require magento/product-community-edition=2.3.0 --no-update

composer update

When running this I get below error. Php version 7.1.26

Problem 1
- magento/module-store 100.1.12 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.26) does not satisfy that requirement.
- magento/module-store 100.1.11 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.26) does not satisfy that requirement.
- magento/module-store 100.1.10 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.26) does not satisfy that requirement.
- magento/module-store 100.1.9 requires php ~5.6.5|7.0.2|7.0.4|~7.0.6 -> your PHP version (7.1.26) does not satisfy that requirement.

How can I solve this?

Answer 1

Try this

php -d memory_limit=-1 /usr/local/bin/composer update --ignore-platform-reqs

--ignore-platform-reqs : ignore php, hhvm, lib-* and ext-* requirements and force the installation even if the local machine does not fulfill these.

Answer 2

Please update your PHP version equal and upper then 7.1.3+.

Please check below Magento official document of support PHP version of M2.3.x.

https://devdocs.magento.com/guides/v2.3/install-gde/system-requirements-tech.html