polyfill-util | component provides binary-safe string functions | Web Framework library

When I do a composer update on my symfony 3.4.30 installation, it completes without problem, but when I try running composer install on the created lock file, it throws an error.

This happens both on my CentOS server, and my MacOS laptop. I have the latest composer installed:

Anyone know what is going on?

I have tried completely removing the vendor directory, and the composer.lock file with no success. I have also updated my composer version, and also cleared my composer cache:

PHP version:

A few months ago, we upgraded the intranet of our company from Symfony 2.3 to Symfony 2.8 and from PHP 5.6 to 7.0.10. Then, we encountered a lot of "Fatal Errors" due to circular references that could be "erased" by restarting Wampserver. I read that this could be because of passing some parameters to services. I corrected this by passing and setting as property only the container, even if I'm not convinced that this is a good practice. I also read that it could be because of opcache, so I disabled this.

After that, we no longer have this problem. However, since two weeks a new "Fatal error" appears randomly :

before i was stuck with this problem the project was running on PHP5.6 on SF2.6.

now im using PHP7.1.20 with SF2.8. i installed apcu along with apcu_bc inside my docker container and enabled the apcu php module.

now the error is:

inside the oficial documentation it say as a first step

$ composer require friendsofsymfony/user-bundle "~2.0"

And this return me this errors

I have a Symfony 3.4 project and code from an old project (SF 2.1) - I want to migrade the code from the old project to the new one. In none of these both projects exists any service.

By running php bin/console I get the error Circular reference detected for service "routing.loader", path: "routing.loader". -> nothing works.

Exception trace:

Reference:
FatalErrorException in Inflector.php line 265: syntax error, unexpected ':', expecting ';' or '{'

I have Laravel 5.3.31 installed along with PHP 5.6.32, however, it seems that composer cannot install the correct version of Doctrine and Symfony as I continue to get the error referenced above even after removing the vendor directory and composer.lock file and running composer install.

I have even modified the composer.json file as shown below.

I have installed composer and downloaded a Symfony app from the git server and am having issues when doing a composer install or update (same issues). Here is the output from an update:

When I try to deploy my symfony app to heroku the deployment fails because it can not connect to the database. I have created a parameters.dist.yml file which is read by composer during the deployment to create the parameters.yml file. I have confirmed that the parameters are correct and can connect to my JawsDB database from my local machine. What could I be doing wrong?

Please see the response from heroku below: