Why do I get this exception?

I'm getting this error constantly and I can't quite figure out what's wrong.

TypeError: strpos(): Argument #1 ($haystack) must be of type string, array given in strpos() (line 126 of core/lib/Drupal/Core/Extension/Dependency.php).
strpos(Array, ':') (Line: 126)
Drupal\Core\Extension\Dependency::createFromString(Array) (Line: 228)
Drupal\Core\Extension\ModuleHandler->buildModuleDependencies(Array) (Line: 169)
Drupal\Core\Extension\ModuleExtensionList->doList() (Line: 282)
Drupal\Core\Extension\ExtensionList->getList() (Line: 143)
Drupal\update\UpdateManager->getProjects() (Line: 283)
update_get_available() (Line: 38)
update_requirements('runtime') (Line: 96)
update_page_top(Array) (Line: 356)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent{closure}(Object, 'update') (Line: 405)
Drupal\Core\Extension\ModuleHandler->invokeAllWith('page_top', Object) (Line: 357)
Drupal\Core\Render\MainContent\HtmlRenderer->buildPageTopAndBottom(Array) (Line: 150)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object) call_user_func(Array, Object, 'kernel.view', Object) (Line: 142)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'kernel.view') (Line: 174)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 81)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 718)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

This error is caused by an incorrect *.info.yml file.

A correct example would be:

media.info.yml

name: Media
description: 'Manages the creation, configuration, and display of media items.'
type: module
package: Core
version: VERSION
dependencies:
  - drupal:file
  - drupal:image
  - drupal:user
configure: media.settings

Where you can see that in dependencies each value is a string. You have installed a module where the *.info.yml file contains a subarray instead.