Release of Daml SDK 1.4.0

Daml SDK 1.4.0 has been released 12th August 2020. You can install it using:

daml install latest

This upgrade should require no action for almost all users. For a few special cases please see the Impact and Migration section below.

Interested in what's happening in the Daml community and broader ecosystem? If so we've got a juicy summary for you in our 1.4.0 announcement post.


  • Daml on SQL is available as an Early Access standalone JAR, you can find it on the GH Release page
  • Improvements to Ledger API and documentation for client application failover
    • This involves changes in the Ledger API in corner cases, but unless you are dealing with application failover, you are unlikely to be affected.
  • Daml REPL is stable and has gained new features, including the ability to run without being connected to a ledger
    • Module imports now need to be made explicit when starting Daml REPL
  • daml codegen js is significantly faster when generating Javascript/TypeScript code
  • New Previous/Next buttons on Thanks to Alex Mason for the suggestion!

Impact and Migration

Migration from SDK 1.3 to 1.4 should require no action for almost all users. 

  • If you were using the Early Access version of Daml REPL, you need to make a minor adjustment to the CLI parameters to start it.
  • If you are working on application failover, you need to incorporate some API improvements.

Standalone Early Access release of Daml on SQL


The Daml Sandbox’s primary purpose is to serve as an in-memory development tool, but has had support for SQL backing for a long time. This made it a popular choice as a prototyping ledger and test tool, but lacking a separate distribution, required an entire SDK installation to run. To add clarity and ease deployment, the developer tool “Sandbox”, and the Ledger “Daml on SQL” are now being separated. As a first step, Daml on SQL is now available as a standalone JAR file on GitHub releases. Some minor changes to functionality and CLI are planned for upcoming releases to further differentiate developer tooling and actual Ledger. The standalone JAR will remain in Early Access until those changes have been made.

Specific Changes

Impact and Migration

For now, this is a purely additive change, but at the same time Daml on SQL will become stable, persistence mode in Sandbox will be deprecated, and after a transition period, both support for persistence in Sandbox, and the already deprecated Sandbox-classic will be removed from the SDK. Users of Sandbox-classic or Sandbox with SQL backing are advised to start migrating over to the new Daml on SQL distribution.

Client Application Failover


Client applications have to be able to deal with the possibility that participant nodes become unavailable, for example due to network or hardware failure. For such cases, some Daml Ledgers offer the possibility to run hot (or cold) standbys of participant nodes. When a failover from a primary to a standby node occurs, the client application has to handle the possibility that due to latency or initialization, the standby is not yet fully caught up with the Ledger. Improvements to Ledger API and documentation makes this significantly easier.

Specific Changes

  • The error code for requesting a transaction stream with an offset beyond the ledger end changed from INVALID_ARGUMENT  to OUT_OF_RANGE.
  • The command completion service now validates the offset and returns the OUT_OF_RANGE error if the request offset is beyond the ledger end.
  • Added a documentation section on how to write Daml applications that can fail over between eventually consistent Ledger API endpoints.

Impact and Migration

The behaviour of the transaction and command completion services have changed in cases where an offset beyond ledger end are given. This should only happen if a client application re-connects to a different node which is not fully caught up, so you are only likely to be affected if your application fails over.

If you were relying on the old behaviors (returning INVALID_ARGUMENT, or accepting the argument, respectively), you now need to handle the OUT_OF_RANGE error and implement retry logic. 

REPL is now Stable


Daml REPL, a developer tool to interactively evaluate Daml and interact with Daml Ledgers has been in Early Access since SDK 0.13.55. With this release, it becomes stable, meaning its developer facing APIs are final and won’t break outside of major SDK versions. In addition, it has gained a number of new useful features including the ability to run without being connected to  a Daml Ledger, allowing interactive testing of pure functions, for example.

Specific Changes

  • Run Daml REPL without connecting to a ledger by omitting the --ledger-host and --ledger-port parameters.
  • List the currently imported modules using the REPL command :show imports.
  • Type :help at the REPL prompt to see a list of possible REPL commands.
  • Add and remove module imports using :module [+-] Some.Module.
  • Use let bindings to bind pure expressions
  • The list of DARs passed to Daml REPL can now be empty.
  • The REPL now supports loading multiple DARs specified at  the command line. The DARs are loaded as data-dependencies.
  • The REPL no longer loads modules by default to avoid collisions when multiple DARs are loaded.

Impact and Migration

You now need to either explicitly import all modules of your DAR file using the --import flag, or use :module + … inside the REPL. For example, if you previously started the REPL with

daml repl .daml/dist/script-example-0.0.1.dar

you now need to either run

daml repl .daml/dist/script-example-0.0.1.dar --import script-example

or import modules individually with

:module + ScriptExample

Faster Javascript Codegen


The TypeScript/JavaScript codegen daml codegen js used to generate TypeScript files and then use yarn to compile these to JavaScript and declaration files. The codegen now generates JavaScript and declarations directly, significantly improving speed, and removing the dependency on yarn.

Specific Changes

  • daml codegen js no longer requires yarn and is significantly faster.

Impact and Migration

No action is required to consume this improvement.

Minor Improvements

  • The Daml compiler will now compile type synonyms (type X = Y) into the DAR,whenever possible, and will expose these synonyms via data-dependencies. This works for Daml-LF 1.8 (the current default) and upwards.
  • Daml Ledgers now print detailed log messages whenever a request was rejected due to a failed JWT authentication/authorization, allowing for easier debugging.
  • You can now use daml new project-name --template=template-name instead of daml new project-name template-name. The positional arguments led to confusion so the named version is now preferred, but both continue to work. 
  • Successful package uploads to the Sandbox are now logged on the server. See
  • Sandbox now allows the user to specify the participant ID with the --participant-id switch.
  • The daml ledger commands now accept a --timeout option which can be used to change the timeout for API requests from the default of 30s.
  • You can now specify the version of Sandbox and the JSON API independently of your SDK version by setting platform-version in your daml.yaml. This is useful if you are deploying to a ledger that is running components from a different SDK version. See for details.
  • daml new foobar --template=create-daml-app now properly respects the project name and creates a project called foobar in daml.yaml and package.json instead of hardcoding the name to create-daml-app.
  • Scala codegen has gained support for exercise-by-key commands. See Issue #6466.

Bug and Security fixes

  • Fix an issue in the JavaScript Client Libraries where some recursive types resulted in a stack overflow.
  • The ActiveContractService now only sets the offset in the last response, as intended, instead of in every response element.
  • A bug relating to how Fetch nodes are validated in some Daml ledgers was fixed.

Integration Kit

  • The performance test names have been changed.
    To learn more about the available tests, consult the documentation for the Ledger API Test Tool and run it with --list. Docs:
  • Fixed a bug in the Ledger API test tool that caused the full conformance test suite to be run when trying to run performance tests but using a wrong name. See
  • Truncate GRPC error messages at 4 KB. This ensures that we won't trigger a protocol error when sending errors to the client.
  • Change the callback for contract keys from GlobalKey => Option[ContractId] to  GlobalKeyWithMaintainers => Option[ContractId] in Daml Engine
  • Removed Sandbox specific code from the API intended to be used by ledger integrations. Use the maven coordinates com.daml:participant-integration-api:VERSION instead of com.daml:ledger-api-server or com.daml:sandbox.
  • StandaloneApiServer can now be run in a read-only mode
    • The type of the constructor parameter writeService of StandaloneApiServer changed to Option[WriteService]. Passing None will not start any of the admin services, the command service, and the command submission service.
    • The constructor parameter readService of StandaloneApiServer has been removed.
    • A new constructor parameter ledgerId has been added to StandaloneApiServer. It is used to verify that StandaloneApiServer is run against an index storage for the same ledgerId. Initialization is aborted if this is not the case.
  • The LedgerConfigurationService now properly streams configuration changes.
  • Default new Engine constructor to Engine.StableConfig so it does not need to be overridden unless you specifically want to run in Engine.DevConfig mode
  • The LotsOfPartiesIT and TransactionScaleIT test suite have been deemed not providing relevant signal to Daml ledger implementers and have been retired. The tests will be nominally kept in but will be skipped while they are in a deprecation period. You are advised to remove explicit references to those tests before they are fully removed.
  • All tests are now run by default. The --all-tests option is now ineffective and deprecated. You are advised to remove its usages from your build scripts. Non-isolated tests that could affect the global state of the ledger and interfere with other tests are now automatically scheduled by the test tool to run sequentially at the end of the run.
  • The --load-scale-factor option is now unused and deprecated. You are advised to remove its usages from your build scripts.

What’s Coming

We are continuing to work on performance of the Daml integration components and improving production readiness of Daml Ledgers, but there are exciting features and improvements in the pipeline for the next few releases as well.

  • The Trigger Service will feature completion and move into Beta
  • The authentication framework for Daml client applications (like the Trigger Service) is being revisited to make it more flexible (and secure!)
  • The build process for Daml client applications using the JavaScript/TypeScript tooling is being improved to remove the most common error scenarios
  • Daml’s error and execution semantics are being tidied up with a view towards improving exception handling in Daml
  • Daml Script is coming to the IDE to supersede Scenarios and give a single scripting interface all the way from unit testing in the IDE to interacting with a production ledger
  • Daml will get a generic Map type as part of Daml-LF 1.9