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Diagnostics include errors, warnings, messages, runtimes, and other context/metadata from when a target was built or an import was processed. If your target's last build succeeded, then diagnose(your_target) has the most current information from that build. But if your target failed, then only diagnose(your_target)$error, diagnose(your_target)$warnings, and diagnose(your_target)$messages correspond to the failure, and all the other metadata correspond to the last build that completed without an error.


  target = NULL,
  character_only = FALSE,
  path = NULL,
  search = NULL,
  cache = drake::drake_cache(path = path),
  verbose = 1L



Name of the target of the error to get. Can be a symbol if character_only is FALSE, must be a character if character_only is TRUE.


Logical, whether target should be treated as a character or a symbol. Just like character.only in library().


Path to a drake cache (usually a hidden .drake/ folder) or NULL.




drake cache. See new_cache(). If supplied, path is ignored.


Deprecated on 2019-09-11.


Either a character vector of target names or an object of class "error".


if (FALSE) {
isolate_example("Quarantine side effects.", {
diagnose() # List all the targets with recorded error logs.
# Define a function doomed to failure.
f <- function() {
  stop("unusual error")
# Create a workflow plan doomed to failure.
bad_plan <- drake_plan(my_target = f())
# Running the project should generate an error
# when trying to build 'my_target'.
try(make(bad_plan), silent = FALSE)
drake_failed() # List the failed targets from the last make() (my_target).
# List targets that failed at one point or another
# over the course of the project (my_target).
# drake keeps all the error logs.
# Get the error log, an object of class "error".
error <- diagnose(my_target)$error # See also warnings and messages.
str(error) # See what's inside the error log.
error$calls # View the traceback. (See the rlang::trace_back() function).