Compatibility Guidelines

Binary Compatibility Rules

Akka HTTP follows the same binary compatibility rules as Akka itself. In short it means that the versioning scheme should be read as major.minor.patch, wherein all versions with the same major version are backwards binary-compatible, with the exception of @ApiMayChange, @InternalApi or @DoNotInherit marked APIs or other specifically documented special-cases.

For more information and a detailed discussion of these rules and guarantees please refer to The @DoNotInherit and @ApiMayChange markers.

Specific versions inter-op discussion

In this section we discuss some of the specific cases of compatibility between versions of Akka HTTP and Akka itself.

For example, you may be interested in those examples if you encountered the following exception in your system when upgrading parts of your libraries: Detected java.lang.NoSuchMethodError error, which MAY be caused by incompatible Akka versions on the classpath. Please note that a given Akka version MUST be the same across all modules of Akka that you are using, e.g. if you use akka-actor [2.5.3 (resolved from current classpath)] all other core Akka modules MUST be of the same version. External projects like Alpakka, Persistence plugins or Akka HTTP etc. have their own version numbers - please make sure you're using a compatible set of libraries.

Akka HTTP 10.0.x with Akka 2.5.x

Akka HTTP 10.0.x is (binary) compatible with both Akka 2.4.x as well as Akka 2.5.x, however in order to facilitate this the build (and thus released artifacts) depend on the 2.4 series. Depending on how you structure your dependencies, you may encounter a situation where you depended on akka-actor of the 2.5 series, and you depend on akka-http from the 10.0 series, which in turn would transitively pull in the akka-streams dependency in version 2.4 which breaks the binary compatibility requirement that all Akka modules must be of the same version, so the akka-streams dependency MUST be the same version as akka-actor (so the exact version from the 2.5 series).

In order to resolve this dependency issue, you must depend on akka-streams explicitly, and make it the same version as the rest of your Akka environment, for example like this:

val akkaVersion = "2.5.4"
val akkaHttpVersion = "10.0.10"
libraryDependencies += "com.typesafe.akka" %% "akka-http"   % akkaHttpVersion
libraryDependencies += "com.typesafe.akka" %% "akka-actor"  % akkaVersion
libraryDependencies += "com.typesafe.akka" %% "akka-stream" % akkaVersion
compile group: 'com.typesafe.akka', name: 'akka-http_2.12', version: '10.0.10'
compile group: 'com.typesafe.akka', name: 'akka-actor_2.12', version: '2.5.4'
compile group: 'com.typesafe.akka', name: 'akka-stream_2.12', version: '2.5.4'
<!-- Explicitly depend on akka-streams in same version as akka-actor-->
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