php bin/console debug:container command outputs an error:

[Symfony\Component\DependencyInjection\Exception\InvalidArgumentException]
Unable to parse file "/home/my-project-path/var/cache/dev/appDevDebugProjectContainer.xml"

[InvalidArgumentException]
[ERROR 522] Validation failed: no DTD found ! (in n/a - line 2, column 46)
[ERROR 9] PCDATA invalid Char value 24 (in n/a - line 26, column 20)
[ERROR 9] PCDATA invalid Char value 24 (in n/a - line 1907, column 23)

tried to clear the cache, but the problem persists.
Symfony v3.0.0 standard edition was used on PHP 5.5.9-1ubuntu4.14 (cli) (built: Oct 28 2015 01:34:46)

Actual XML in the path defined begins with:

    <?xml version="1.0" encoding="utf-8"?>
    <container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">