how to fix error occurred during upgrade magento from 2.2 to 2.3 ?

[yagnik_solanki]

Process :  Upgrade magento version from 2.2 to 2.3

As per my client requirement, i was tried to upgrade magento from 2.2 to 2.3 as per mention into this site : https://devdocs.magento.com/guides/v2.3/comp-mgr/cli/cli-upgrade.html

All steps were ran properly but after run "composer update" command it will throw following Fatal error after sometime as per mention into screenshot .

And  then after exit from "composer update" command.

Please suggest me how can i fix this error ?.

Thanks in advance.

[kgerasimov]

Wild guess - you either using a wrong version of composer OR composer is using a wrong version of PHP.

You might want to just copy/paste the latest M2.3.

[yagnik_solanki]

Thanks for reply,

In my client server, PHP version is 7.2.16, Composer Version  is 1.8 and Magento version is 2.2.6.

Configuration of client server satisfy all requirements of Magento 2.3 

And my client wants to upgrade current site version to latest, So i am try to upgrade version to 2.3.0 from 2.2.6 as per mention into magento documents.

Above mention error occurred after run composer update command.

Please let me know if you have another solution.

[yagnik_solanki]

Hi,

I fixed above issue my way and magento was upgraded to 2.3.0