"ERROR: Unsupported Media Type" when trying to use az rest #32972
Description
Describe the bug
Getting subj error when calling put command. Went through other issues. Tried single line, backslash encoded, bash/PS. Always the same. I know people who can run this without issues. What could be misconfigured in my environment?
Related command
az rest --uri /subscriptions/$subId/resourceGroups/$rg/providers/Microsoft.Web/sites/$appname/config/authsettings?api-version=2020-09-01 --method put --body auth4.json
Errors
Unsupported Media Type({"error":{"code":"UnsupportedMediaType","message":"The content media type '' is not supported. Only 'application/json' is supported."}})
Issue script & Debug output
PS C:\Users\xxx> az rest --uri /subscriptions/9f64276cxxx/resourceGroups/xxx/providers/Microsoft.Web/sites/xxx/config/authsettings?api-version=2020-09-01 --method put --body auth4.json --debug
cli.knack.cli: Command arguments: ['rest', '--uri', '/subscriptions/9f64276cxxx/resourceGroups/xxx/providers/Microsoft.Web/sites/xxx/config/authsettings?api-version=2020-09-01', '--method', 'put', '--body', 'auth4.json', '--debug']
cli.knack.cli: init debug log:
Enable color in terminal.
cli.knack.cli: Event: Cli.PreExecute []
cli.knack.cli: Event: CommandParser.OnGlobalArgumentsCreate [<function CLILogging.on_global_arguments at 0x0000019D19C85300>, <function OutputProducer.on_global_arguments at 0x0000019D1A2368E0>, <function CLIQuery.on_global_arguments at 0x0000019D1A280860>]
cli.knack.cli: Event: CommandInvoker.OnPreCommandTableCreate []
cli.azure.cli.core: Modules found from index for 'rest': ['azure.cli.command_modules.util']
cli.azure.cli.core: Loading command modules...
cli.azure.cli.core: Loaded command modules in parallel:
cli.azure.cli.core: Name Load Time Groups Commands
cli.azure.cli.core: util 0.003 3 7
cli.azure.cli.core: Total (1) 0.004 3 7
cli.azure.cli.core: These extensions are not installed and will be skipped: ['azext_ai_examples', 'azext_next']
cli.azure.cli.core: Loading extensions:
cli.azure.cli.core: Name Load Time Groups Commands Directory
cli.azure.cli.core: Total (0) 0.000 0 0
cli.azure.cli.core: Loaded 3 groups, 7 commands.
cli.azure.cli.core: Found a match in the command table.
cli.azure.cli.core: Raw command : rest
cli.azure.cli.core: Command table: rest
cli.knack.cli: Event: CommandInvoker.OnPreCommandTableTruncate [<function AzCliLogging.init_command_file_logging at 0x0000019D1CA21080>]
cli.azure.cli.core.azlogging: metadata file logging enabled - writing logs to 'C:\Users\xxx.azure\commands\2026-03-15.14-01-52.rest.32168.log'.
az_command_data_logger: command args: rest --uri {} --method {} --body {} --debug
cli.knack.cli: Event: CommandInvoker.OnPreArgumentLoad [<function register_global_subscription_argument..add_subscription_parameter at 0x0000019D1CA6EDE0>]
cli.knack.cli: Event: CommandInvoker.OnPostArgumentLoad []
cli.knack.cli: Event: CommandInvoker.OnPostCommandTableCreate [<function register_ids_argument..add_ids_arguments at 0x0000019D1CA9D120>, <function register_cache_arguments..add_cache_arguments at 0x0000019D1CA9D300>, <function register_upcoming_breaking_change_info..update_breaking_change_info at 0x0000019D1CA9D3A0>]
cli.knack.cli: Event: CommandInvoker.OnCommandTableLoaded []
cli.knack.cli: Event: CommandInvoker.OnPreParseArgs []
cli.knack.cli: Event: CommandInvoker.OnPostParseArgs [<function OutputProducer.handle_output_argument at 0x0000019D1A236980>, <function CLIQuery.handle_query_parameter at 0x0000019D1A280900>, <function register_ids_argument..parse_ids_arguments at 0x0000019D1CA9D1C0>]
cli.azure.cli.core.util: malformed node or string on line 1: <ast.Attribute object at 0x0000019D1CE0F6D0>
cli.azure.cli.core.util: Found subscription ID 9f64276c-749d-40d4-948b-96c6ec4c3102 in the URL https://management.azure.com/subscriptions/9f64276c-749d-40d4-948b-96c6ec4c3102/resourceGroups/xxx/providers/Microsoft.Web/sites/xxx/config/authsettings?api-version=2020-09-01
cli.azure.cli.core.util: Retrieving token for resource https://management.core.windows.net/, subscription 9f64276cxxx
cli.azure.cli.core.auth.persistence: build_persistence: location='C:\Users\xxx\.azure\msal_token_cache.bin', encrypt=True
cli.azure.cli.core.auth.binary_cache: load: C:\Users\xxx.azure\msal_http_cache.bin
urllib3.util.retry: Converted retries value: 1 -> Retry(total=1, connect=None, read=None, redirect=None, status=None)
msal.authority: Initializing with Entra authority: https://login.microsoftonline.com/b0f12464-xxx
msal.authority: openid_config("https://login.microsoftonline.com/b0f12464-xxx/v2.0/.well-known/openid-configuration") = {'token_endpoint': 'https://login.microsoftonline.com/b0f12464-121f-4db3-82de-1b9f93eb34e6/oauth2/v2.0/token', 'token_endpoint_auth_methods_supported': ['client_secret_post', 'private_key_jwt', 'client_secret_basic', 'self_signed_tls_client_auth'], 'jwks_uri': 'https://login.microsoftonline.com/b0f12464-xxx/discovery/v2.0/keys', 'response_modes_supported': ['query', 'fragment', 'form_post'], 'subject_types_supported': ['pairwise'], 'id_token_signing_alg_values_supported': ['RS256'], 'response_types_supported': ['code', 'id_token', 'code id_token', 'id_token token'], 'scopes_supported': ['openid', 'profile', 'email', 'offline_access'], 'request_uri_parameter_supported': False, 'userinfo_endpoint': 'https://graph.microsoft.com/oidc/userinfo', 'authorization_endpoint': 'https://login.microsoftonline.com/b0f12464-121f-4db3-82de-1b9f93eb34e6/oauth2/v2.0/authorize', 'device_authorization_endpoint': 'https://login.microsoftonline.com/b0f12464-121f-4db3-82de-1b9f93eb34e6/oauth2/v2.0/devicecode', 'http_logout_supported': True, 'frontchannel_logout_supported': True, 'end_session_endpoint': 'https://login.microsoftonline.com/b0f12464xxx/oauth2/v2.0/logout', 'claims_supported': ['sub', 'iss', 'cloud_instance_name', 'cloud_instance_host_name', 'cloud_graph_host_name', 'msgraph_host', 'aud', 'exp', 'iat', 'auth_time', 'acr', 'nonce', 'preferred_username', 'name', 'tid', 'ver', 'at_hash', 'c_hash', 'email'], 'kerberos_endpoint': 'https://login.microsoftonline.com/b0f12464-121f-4db3-82de-1b9f93eb34e6/kerberos', 'mtls_endpoint_aliases': {'token_endpoint': 'https://mtlsauth.microsoft.com/b0f12464-xxx/oauth2/v2.0/token'}, 'tls_client_certificate_bound_access_tokens': True, 'tenant_region_scope': 'NA', 'cloud_instance_name': 'microsoftonline.com', 'cloud_graph_host_name': 'graph.windows.net', 'msgraph_host': 'graph.microsoft.com', 'rbac_url': 'https://pas.windows.net'}
msal.application: Broker enabled? True
cli.azure.cli.core.auth.msal_credentials: UserCredential.acquire_token: scopes=['https://management.core.windows.net//.default'], claims_challenge=None, kwargs={}
msal.application: Cache hit an AT
msal.telemetry: Generate or reuse correlation_id: 0bfb996c-9d66-4a10-a8d6-0911e2ba3161
cli.azure.cli.core.util: Request URL: 'https://management.azure.com/subscriptions/9f64276c-xxx/resourceGroups/xxx/providers/Microsoft.Web/sites/xxx/config/authsettings?api-version=2020-09-01'
cli.azure.cli.core.util: Request method: 'PUT'
cli.azure.cli.core.util: Request headers:
cli.azure.cli.core.util: 'User-Agent': 'python/3.13.11 (Windows-11-10.0.26100-SP0) AZURECLI/2.84.0 (MSI)'
cli.azure.cli.core.util: 'Accept-Encoding': 'gzip, deflate'
cli.azure.cli.core.util: 'Accept': '/'
cli.azure.cli.core.util: 'Connection': 'keep-alive'
cli.azure.cli.core.util: 'x-ms-client-request-id': '1df6e966-853c-4539-bed9-e543cf5f49d0'
cli.azure.cli.core.util: 'CommandName': 'rest'
cli.azure.cli.core.util: 'ParameterSetName': '--uri --method --body --debug'
cli.azure.cli.core.util: 'Authorization': 'Bearer eyJ0eXAiOiJKV...'
cli.azure.cli.core.util: 'Content-Length': '10'
cli.azure.cli.core.util: Request body:
cli.azure.cli.core.util: auth4.json
urllib3.connectionpool: Starting new HTTPS connection (1): management.azure.com:443
urllib3.connectionpool: https://management.azure.com:443 "PUT /subscriptions/9f64276c-xxx/resourceGroups/xxx/providers/Microsoft.Web/sites/xxx/config/authsettings?api-version=2020-09-01 HTTP/1.1" 415 141
cli.azure.cli.core.util: Response status: 415
cli.azure.cli.core.util: Response headers:
cli.azure.cli.core.util: 'Cache-Control': 'no-cache'
cli.azure.cli.core.util: 'Pragma': 'no-cache'
cli.azure.cli.core.util: 'Content-Length': '141'
cli.azure.cli.core.util: 'Content-Type': 'application/json; charset=utf-8'
cli.azure.cli.core.util: 'Expires': '-1'
cli.azure.cli.core.util: 'x-ms-failure-cause': 'gateway'
cli.azure.cli.core.util: 'x-ms-request-id': '72da21e0-77aa-4e3c-8cd1-f45816200914'
cli.azure.cli.core.util: 'x-ms-correlation-request-id': '72da21e0-77aa-4e3c-8cd1-f45816200914'
cli.azure.cli.core.util: 'x-ms-routing-request-id': 'CENTRALUS:20260315T210153Z:72da21e0-77aa-4e3c-8cd1-f45816200914'
cli.azure.cli.core.util: 'Strict-Transport-Security': 'max-age=31536000; includeSubDomains'
cli.azure.cli.core.util: 'X-Content-Type-Options': 'nosniff'
cli.azure.cli.core.util: 'X-Cache': 'CONFIG_NOCACHE'
cli.azure.cli.core.util: 'X-MSEdge-Ref': 'Ref A: 897BAE7A8DFB4E2DBE399566BF6851FC Ref B: CO6AA3150220021 Ref C: 2026-03-15T21:01:53Z'
cli.azure.cli.core.util: 'Date': 'Sun, 15 Mar 2026 21:01:52 GMT'
cli.azure.cli.core.util: Response content:
cli.azure.cli.core.util: {"error":{"code":"UnsupportedMediaType","message":"The content media type '' is not supported. Only 'application/json' is supported."}}
cli.azure.cli.core.azclierror: Traceback (most recent call last):
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\knack/cli.py", line 233, in invoke
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/core/commands/init.py", line 682, in execute
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/core/commands/init.py", line 812, in _run_jobs_serially
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/core/commands/init.py", line 781, in _run_job
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/core/commands/init.py", line 336, in call
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/core/commands/command_operation.py", line 120, in handler
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/command_modules/util/custom.py", line 24, in rest_call
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/core/util.py", line 1096, in send_raw_request
azure.cli.core.azclierror.HTTPError: Unsupported Media Type({"error":{"code":"UnsupportedMediaType","message":"The content media type '' is not supported. Only 'application/json' is supported."}})
cli.azure.cli.core.azclierror: Unsupported Media Type({"error":{"code":"UnsupportedMediaType","message":"The content media type '' is not supported. Only 'application/json' is supported."}})
az_command_data_logger: Unsupported Media Type({"error":{"code":"UnsupportedMediaType","message":"The content media type '' is not supported. Only 'application/json' is supported."}})
cli.knack.cli: Event: Cli.PostExecute [<function AzCliLogging.deinit_cmd_metadata_logging at 0x0000019D1CA21300>]
az_command_data_logger: exit code: 1
cli.main: Command ran in 1.256 seconds (init: 0.335, invoke: 0.920)
cli.azure.cli.core.decorators: Suppress exception:
Traceback (most recent call last):
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/main.py", line 53, in
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/main.py", line 46, in
SystemExit: 1
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/core/decorators.py", line 79, in wrapped_func
File "D:\a_work\1\s\build_scripts\windows\artifacts\cli\Lib\site-packages\azure/cli/core/telemetry.py", line 131, in generate_payload
File "json_init.py", line 242, in dumps
File "json\encoder.py", line 202, in encode
File "json\encoder.py", line 263, in iterencode
File "json\encoder.py", line 182, in default
TypeError: Object of type HTTPError is not JSON serializable
telemetry.main: Split cli events and extra events failure: the JSON object must be str, bytes or bytearray, not NoneType
Expected behavior
Expected behavior is that the Content-Type header is set by default to application/json as per the az rest documentation here:
https://learn.microsoft.com/en-us/cli/azure/reference-index?view=azure-cli-latest#az-rest
Then that the HTTP 2.0 Proxy flag is set correctly and that the response from az rest returns the updated state of the resource rather than an error.
Environment Summary
azure-cli 2.84.0
core 2.84.0
telemetry 1.1.0
Extensions:
authV2 0.1.1
Dependencies:
msal 1.35.0b1
azure-mgmt-resource 24.0.0
Python location 'C:\Program Files\Microsoft SDKs\Azure\CLI2\python.exe'
Config directory 'C:\Users\xxx.azure'
Extensions directory 'C:\Users\xxx.azure\cliextensions'
Python (Windows) 3.13.11 (tags/v3.13.11:6278944, Dec 5 2025, 16:26:58) [MSC v.1944 64 bit (AMD64)]
Additional context
No response