Configuration
variable_del() has been removed.
Documentation
Files Affected
variable_get() has been removed.
Documentation
Files Affected
variable_set() has been removed.
Documentation
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Default configuration is deleted automatically.
Files Affected
Entity API
user_load() has been removed.
Documentation
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user_save() has been removed.
Documentation
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Form API
drupal_map_assoc() has been removed.
Documentation
Files Affected
form_set_error() is now a method of FormStateInterface.
Documentation
Files Affected
Info File
Module info files' core key must have a value of 8.x.
Documentation
Files Affected
Info files must contain a type key.
Documentation
Files Affected
Many common dependencies have moved into core.
Documentation
Files Affected
Modules no longer declare classes in their info file.
Documentation
Files Affected
Module info files' configure key must be a route name, not a path.
Documentation
Files Affected
Menu/Routing
hook_menu() has been removed from Drupal 8.
Documentation
Files Affected
hook_menu_alter() has been removed.
Documentation
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current_path() has been replaced by the route.
Documentation
Files Affected
Miscellaneous
Many common functions, shared variables, and constants have been renamed.
Documentation
Classes must be PSR-4 compliant.
Documentation
Automated web tests must be in a PSR-4 namespace, and unit tests must be converted to PHPUnit.
Documentation
System
hook_init() has been removed.
Documentation
Files Affected
drupal_goto() has been removed.
Documentation
Files Affected
l() has been removed.
Documentation
Files Affected
watchdog() has been removed.
Documentation
Files Affected
Theme System
theme() has been renamed to _theme(), and should never be called directly.
Documentation
Files Affected