Error:

- Required package "laravel/framework" is in the lock file as "v5.5.50" but that does not satisfy your constraint "^10.10".
- Required package "laravel/tinker" is in the lock file as "v1.0.10" but that does not satisfy your constraint "^2.8".
- Required package "lcobucci/jwt" is in the lock file as "3.3.3" but that does not satisfy your constraint "4.0".
- Required package "paragonie/random_compat" is in the lock file as "v2.0.20" but that does not satisfy your constraint "^9.99.1".
- Required package "laravel/ui" is not present in the lock file.
- Required (in require-dev) package "mockery/mockery" is in the lock file as "1.3.4" but that does not satisfy your constraint "^1.4.4".
- Required (in require-dev) package "phpunit/phpunit" is in the lock file as "6.5.14" but that does not satisfy your constraint "^10.4.2".
This usually happens when composer files are incorrectly merged or the composer.json file is manually edited.
Read more about correctly resolving merge conflicts https://getcomposer.org/doc/articles/resolving-merge-conflicts.md
and prefer using the "require" command over editing the composer.json file directly https://getcomposer.org/doc/03-cli.md#require-r

Sulotion:

Step 1 : Please update you composer for this command

composer update

Step 2 : Run this command on your project

composer require laravel/helpers

After run again composer update