Scala New Added 9 October 2026

Scala module 2.15.2 requires Jackson Databind version >= 2.15.0 and < 2.16.0

jackson-module-scala refuses to register unless jackson-databind on the classpath has the same minor version, and something else pulled databind up or down. In Spark jobs the usual culprit is the Jackson that Spark itself ships, which is why the job runs locally and fails once submitted to the cluster. The check runs when the module is registered, so it fails at startup rather than at the first JSON call.

Quick fix

Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.

Quick fix

# Which Jackson versions end up on the classpath?
sbt evicted
sbt 'show Runtime/fullClasspath' | tr ',' '\n' | grep jackson

# Pin every Jackson artefact to one version (build.sbt)
val jacksonVersion = "2.15.2"
dependencyOverrides ++= Seq(
  "com.fasterxml.jackson.core" % "jackson-databind" % jacksonVersion,
  "com.fasterxml.jackson.module" %% "jackson-module-scala" % jacksonVersion
)

# Spark: match the version the cluster bundles
ls $SPARK_HOME/jars | grep jackson
# and mark spark-core / spark-sql as "provided" so you do not ship a second copy

How to diagnose Scala errors

Scala's most distinctive error class is binary incompatibility: libraries are published per Scala major version, and mixing artifacts built for different versions produces confusing "not a member of" or NoSuchMethodError failures. The %% operator in sbt exists precisely to append the right suffix, and most unresolved-dependency errors are a % where %% was needed.

If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.

Check the Scala version suffix on every dependency. Use %% for Scala libraries and plain % only for Java ones.
Run sbt evicted to list dependencies that were evicted by version conflict. A frequent source of runtime NoSuchMethodError.
Use sbt dependencyTree to see the resolved graph and locate the transitive dependency pulling in an old version.
For inference failures, add explicit type annotations at the boundary rather than at the error site; inference failures usually propagate from further up.
Clear stale state with sbt clean and remove ~/.ivy2/cache or ~/.cache/coursier entries only for the specific failing artifact.

Tools worth reaching for

sbt evicted
sbt dependencyTree
coursier resolve
scalac -explain
MiMa (binary compat checks)

Authoritative references

Primary documentation for this error, worth reading before applying any fix in production.

github.com scala-sbt.org

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