We're strictly not breaking backwards compatibility in patch releases such as 2.x.y.Z and trying to avoid had to fix
backwards incompatible changes in minor releases such as 2.x.Y.
Check Yii Versioning to learn about version numbering.
| Use case |
BC? |
| Type hint with the interface |
Yes |
| Call the interface method |
Yes |
| Implement the interface and... |
|
| Implement method |
Yes |
| Add argument to method implemented |
Yes |
| Add default value to an argument |
Yes |
| Use case |
BC? |
| Type hint with the class |
Yes |
| Create a new instance |
Yes |
| Extend the class |
Yes |
| Access a public property |
Yes |
| Call a public method |
Yes |
| Extend the class and... |
|
| Access a protected property |
Yes |
| Call a protected method |
Yes |
| Override a public property |
Yes |
| Override a protected property |
Yes |
| Override a public method |
Yes |
| Override a protected method |
Yes |
| Add a new property |
No |
| Add a new method |
No |
| Add an argument to an overridden method |
Yes |
| Add a default value to an argument |
Yes |
| Call a private method (via Reflection) |
No |
| Access a private property (via Reflection) |
No |
| Type of change |
BC? |
| Remove |
No |
| Change name or namespace |
No |
| Add parent interface |
Yes if no new methods are added |
| Remove parent interface |
No |
| Interface methods |
|
| Add method |
No |
| Remove method |
No |
| Change name |
No |
| Move to parent interface |
Yes |
| Add argument without a default value |
No |
| Add argument with a default value |
No |
| Remove argument |
Yes (only last ones) |
| Add default value to an argument |
No |
| Remove default value of an argument |
No |
| Add type hint to an argument |
No |
| Remove type hint of an argument |
No |
| Change argument type |
No |
| Change return type |
No |
| Constants |
|
| Add constant |
Yes |
| Remove constant |
No |
| Change value of a constant |
Yes except objects that are likely to be serialized. Mandatory to document in UPGRADE.md. |
| Type of change |
BC? |
| Remove |
No |
| Make final |
No |
| Make abstract |
No |
| Change name or namespace |
No |
| Change parent class |
Yes but original parent class must remain an ancestor of the class. |
| Add interface |
Yes |
| Remove interface |
No |
| Public Properties |
|
| Add public property |
Yes |
| Remove public property |
No |
| Reduce visibility |
No |
| Move to parent class |
Yes |
| Protected Properties |
|
| Add protected property |
Yes |
| Remove protected property |
No |
| Reduce visibility |
No |
| Move to parent class |
Yes |
| Private Properties |
|
| Add private property |
Yes |
| Remove private property |
Yes |
| Constructors |
|
| Remove constructor |
No |
| Reduce visibility of a public constructor |
No |
| Reduce visibility of a protected constructor |
No |
| Move to parent class |
Yes |
| Public Methods |
|
| Add public method |
Yes |
| Remove public method |
No |
| Change name |
No |
| Reduce visibility |
No |
| Move to parent class |
Yes |
| Add argument without a default value |
No |
| Add argument with a default value |
No |
| Remove arguments |
Yes, only last ones |
| Add default value to an argument |
No |
| Remove default value of an argument |
No |
| Add type hint to an argument |
No |
| Remove type hint of an argument |
No |
| Change argument type |
No |
| Change return type |
No |
| Protected Methods |
|
| Add protected method |
Yes |
| Remove protected method |
No |
| Change name |
No |
| Reduce visibility |
No |
| Move to parent class |
Yes |
| Add argument without a default value |
No |
| Add argument with a default value |
No |
| Remove arguments |
Yes, only last ones |
| Add default value to an argument |
No |
| Remove default value of an argument |
No |
| Add type hint to an argument |
No |
| Remove type hint of an argument |
No |
| Change argument type |
No |
| Change return type |
No |
| Private Methods |
|
| Add private method |
Yes |
| Remove private method |
Yes |
| Change name |
Yes |
| Add argument without a default value |
Yes |
| Add argument with a default value |
Yes |
| Remove argument |
Yes |
| Add default value to an argument |
Yes |
| Remove default value of an argument |
Yes |
| Add type hint to an argument |
Yes |
| Remove type hint of an argument |
Yes |
| Change argument type |
Yes |
| Change return type |
Yes |
| Static Methods |
|
| Turn non static into static |
No |
| Turn static into non static |
No |
| Constants |
|
| Add constant |
Yes |
| Remove constant |
No |
| Change value of a constant |
Yes except objects that are likely to be serialized. Mandatory to document in UPGRADE.md. |