--- a/config/rules.mk
+++ b/config/rules.mk
@@ -920,17 +920,17 @@ define RUN_CARGO
 $(if $(findstring n,$(filter-out --%, $(MAKEFLAGS))),,+)env $(environment_cleaner) $(rust_unlock_unstable) $(rustflags_override) $(sccache_wrap) \
 	CARGO_TARGET_DIR=$(CARGO_TARGET_DIR) \
 	RUSTC=$(RUSTC) \
 	MOZ_SRC=$(topsrcdir) \
 	MOZ_DIST=$(ABS_DIST) \
 	LIBCLANG_PATH="$(MOZ_LIBCLANG_PATH)" \
 	CLANG_PATH="$(MOZ_CLANG_PATH)" \
 	PKG_CONFIG_ALLOW_CROSS=1 \
-	RUST_BACKTRACE=1 \
+	RUST_BACKTRACE=full \
 	MOZ_TOPOBJDIR=$(topobjdir) \
 	$(2) \
 	$(CARGO) $(1) $(cargo_build_flags)
 endef
 
 # This function is intended to be called by:
 #
 #   $(call CARGO_BUILD,EXTRA_ENV_VAR1=X EXTRA_ENV_VAR2=Y ...)

--- a/python/mozbuild/mozbuild/mach_commands.py
+++ b/python/mozbuild/mozbuild/mach_commands.py
@@ -1384,17 +1384,17 @@ class RunProgram(MachCommandBase):
 
             if not no_profile_option_given and setpref:
                 print("setpref is only supported if a profile is not specified")
                 return 1
 
         extra_env = {
             'MOZ_DEVELOPER_REPO_DIR': self.topsrcdir,
             'MOZ_DEVELOPER_OBJ_DIR': self.topobjdir,
-            'RUST_BACKTRACE': '1',
+            'RUST_BACKTRACE': 'full',
         }
 
         if not enable_crash_reporter:
             extra_env['MOZ_CRASHREPORTER_DISABLE'] = '1'
         else:
             extra_env['MOZ_CRASHREPORTER'] = '1'
 
         if disable_e10s:

--- a/testing/mozharness/mozharness/mozilla/testing/firefox_ui_tests.py
+++ b/testing/mozharness/mozharness/mozilla/testing/firefox_ui_tests.py
@@ -247,17 +247,17 @@ class FirefoxUITests(TestingMixin, VCSTo
         tests = [os.path.join(dirs['abs_fxui_dir'], 'tests', test) for test in self.default_tests]
         cmd.extend(tests)
 
         # Set further environment settings
         env = env or self.query_env()
         env.update({'MINIDUMP_SAVE_PATH': dirs['abs_blob_upload_dir']})
         if self.query_minidump_stackwalk():
             env.update({'MINIDUMP_STACKWALK': self.minidump_stackwalk_path})
-        env['RUST_BACKTRACE'] = '1'
+        env['RUST_BACKTRACE'] = 'full'
 
         # If code coverage is enabled, set GCOV_PREFIX and JS_CODE_COVERAGE_OUTPUT_DIR env variables
         if self.config.get('code_coverage'):
             env['GCOV_PREFIX'] = self.gcov_dir
             env['JS_CODE_COVERAGE_OUTPUT_DIR'] = self.jsvm_dir
 
         if self.config['allow_software_gl_layers']:
             env['MOZ_LAYERS_ALLOW_SOFTWARE_GL'] = '1'

--- a/testing/mozharness/mozharness/mozilla/testing/talos.py
+++ b/testing/mozharness/mozharness/mozilla/testing/talos.py
@@ -540,17 +540,17 @@ class Talos(TestingMixin, MercurialScrip
         self.run_command([python, "--version"])
         parser = TalosOutputParser(config=self.config, log_obj=self.log_obj,
                                    error_list=TalosErrorList)
         env = {}
         env['MOZ_UPLOAD_DIR'] = self.query_abs_dirs()['abs_blob_upload_dir']
         if not self.run_local:
             env['MINIDUMP_STACKWALK'] = self.query_minidump_stackwalk()
         env['MINIDUMP_SAVE_PATH'] = self.query_abs_dirs()['abs_blob_upload_dir']
-        env['RUST_BACKTRACE'] = '1'
+        env['RUST_BACKTRACE'] = 'full'
         if not os.path.isdir(env['MOZ_UPLOAD_DIR']):
             self.mkdir_p(env['MOZ_UPLOAD_DIR'])
         env = self.query_env(partial_env=env, log_level=INFO)
         # adjust PYTHONPATH to be able to use talos as a python package
         if 'PYTHONPATH' in env:
             env['PYTHONPATH'] = self.talos_path + os.pathsep + env['PYTHONPATH']
         else:
             env['PYTHONPATH'] = self.talos_path

--- a/testing/mozharness/scripts/android_emulator_unittest.py
+++ b/testing/mozharness/scripts/android_emulator_unittest.py
@@ -717,17 +717,17 @@ class AndroidEmulatorTest(BlobUploadMixi
             cwd = self._query_tests_dir()
         except:
             self.fatal("Don't know how to run --test-suite '%s'!" % self.test_suite)
         env = self.query_env()
         if self.query_minidump_stackwalk():
             env['MINIDUMP_STACKWALK'] = self.minidump_stackwalk_path
         env['MOZ_UPLOAD_DIR'] = self.query_abs_dirs()['abs_blob_upload_dir']
         env['MINIDUMP_SAVE_PATH'] = self.query_abs_dirs()['abs_blob_upload_dir']
-        env['RUST_BACKTRACE'] = '1'
+        env['RUST_BACKTRACE'] = 'full'
 
         self.info("Running on %s the command %s" % (self.emulator["name"], subprocess.list2cmdline(cmd)))
         self.info("##### %s log begins" % self.test_suite)
 
         # TinderBoxPrintRe does not know about the '-debug' categories
         aliases = {
             'reftest-debug': 'reftest',
             'jsreftest-debug': 'jsreftest',

--- a/testing/mozharness/scripts/desktop_unittest.py
+++ b/testing/mozharness/scripts/desktop_unittest.py
@@ -704,17 +704,17 @@ class DesktopUnittest(TestingMixin, Merc
                     parser.formatter = ref_formatter.ReftestFormatter()
 
                 if self.query_minidump_stackwalk():
                     env['MINIDUMP_STACKWALK'] = self.minidump_stackwalk_path
                 if self.query_nodejs():
                     env['MOZ_NODE_PATH'] = self.nodejs_path
                 env['MOZ_UPLOAD_DIR'] = self.query_abs_dirs()['abs_blob_upload_dir']
                 env['MINIDUMP_SAVE_PATH'] = self.query_abs_dirs()['abs_blob_upload_dir']
-                env['RUST_BACKTRACE'] = '1'
+                env['RUST_BACKTRACE'] = 'full'
                 if not os.path.isdir(env['MOZ_UPLOAD_DIR']):
                     self.mkdir_p(env['MOZ_UPLOAD_DIR'])
 
                 if self.config['allow_software_gl_layers']:
                     env['MOZ_LAYERS_ALLOW_SOFTWARE_GL'] = '1'
                 if self.config['enable_webrender']:
                     env['MOZ_WEBRENDER'] = '1'
 

--- a/testing/mozharness/scripts/marionette.py
+++ b/testing/mozharness/scripts/marionette.py
@@ -311,17 +311,17 @@ class MarionetteTest(TestingMixin, Mercu
         cmd.extend(self.query_tests_args(try_tests,
                                          str_format_values=config_fmt_args))
 
         env = {}
         if self.query_minidump_stackwalk():
             env['MINIDUMP_STACKWALK'] = self.minidump_stackwalk_path
         env['MOZ_UPLOAD_DIR'] = self.query_abs_dirs()['abs_blob_upload_dir']
         env['MINIDUMP_SAVE_PATH'] = self.query_abs_dirs()['abs_blob_upload_dir']
-        env['RUST_BACKTRACE'] = '1'
+        env['RUST_BACKTRACE'] = 'full'
 
         if self.config['allow_software_gl_layers']:
             env['MOZ_LAYERS_ALLOW_SOFTWARE_GL'] = '1'
         if self.config['enable_webrender']:
             env['MOZ_WEBRENDER'] = '1'
 
         if not os.path.isdir(env['MOZ_UPLOAD_DIR']):
             self.mkdir_p(env['MOZ_UPLOAD_DIR'])

--- a/testing/mozharness/scripts/web_platform_tests.py
+++ b/testing/mozharness/scripts/web_platform_tests.py
@@ -273,17 +273,17 @@ class WebPlatformTest(TestingMixin, Merc
         self._install_fonts()
 
         parser = StructuredOutputParser(config=self.config,
                                         log_obj=self.log_obj,
                                         log_compact=True,
                                         error_list=BaseErrorList + HarnessErrorList)
 
         env = {'MINIDUMP_SAVE_PATH': dirs['abs_blob_upload_dir']}
-        env['RUST_BACKTRACE'] = '1'
+        env['RUST_BACKTRACE'] = 'full'
 
         if self.config['allow_software_gl_layers']:
             env['MOZ_LAYERS_ALLOW_SOFTWARE_GL'] = '1'
         if self.config['enable_webrender']:
             env['MOZ_WEBRENDER'] = '1'
         if self.config['headless']:
             env['MOZ_HEADLESS'] = '1'
             env['MOZ_HEADLESS_WIDTH'] = self.config['headless_width']