topic Re: FMC 6.3 "unprocessable entity" error when trying to amen in Network Security

FMC 6.3 "unprocessable entity" error when trying to amend access rule

Sergey Lisitsin — Fri, 01 Mar 2019 12:46:01 GMT

Good afternoon everyone,

I'm trying to amend an existing access rule to enable logging on it. I read the policy and the rule fine. I get the rule output in a variable called data. Then I amend 'logFiles' field from 'False' to 'True' and try to execute a put request with it as the data. Then I get unprocessable entity error. Can anyone explain why it is?

The FMC version is 6.3, I am using Python 3.

Thanks,

Sergey.

Re: FMC 6.3 "unprocessable entity" error when trying to amend access rule

eckdd — Mon, 18 Feb 2019 21:42:40 GMT

I believe "unprocessable entity" errors usually happen when an element in your JSON does contain a valid value, has an non-existent property, or is just improperly formatted. If you have a way to output the JSON you're sending, check for any empty or null values. I have also seen the API be case-sensitive, so play around with True/true/TRUE.

Re: FMC 6.3 "unprocessable entity" error when trying to amen

tyoung008 — Tue, 24 Jun 2025 14:29:14 GMT

EDIT 06/24/25 - This post is not correct. Please see my post below.

https://www.keycdn.com/support/422-unprocessable-entity

The FMC understands the content type of the request entity and the syntax of the request entity is correct but was unable to process the contained instructions. It is not a 400 (Bad Request) which usually happens when a parameter is wrong on you try to post an entry that already exists. You are doing a put, which is correct. Conclusion: This is not an easy syntax fix. Try to manual make the change on the FMC, and see it you get an error.

Re: FMC 6.3 "unprocessable entity" error when trying to amen

tyoung008 — Tue, 24 Jun 2025 14:35:02 GMT

EDIT 06/24/25 - The JSON syntax is correct, but a value is incorrect. The specific error will be returned in the JSON response. For Python requests module, use the following code to return the error:

response = requests.request(...) resp_dict = json.loads(response.text) error_msg = resp_dict['error']['messages'][0]['description']

Original Post - This is cool, although it counters the info I gave above which is RFC standard, https://tools.ietf.org/html/rfc4918#section-11.2. In my experience syntax errors return an HTTP 400.

https://www.cisco.com/c/en/us/td/docs/security/firepower/623/api/REST/Firepower_Management_Center_REST_API_Quick_Start_Guide_623/Objects_in_the_REST_API.html

```
422 Unprocessable Entity
```
– The payload is too large. This will occur when you send a payload greater than 2048000 bytes.
– The payload contains an unprocessable or unreadable entity such as a invalid attribut name or incorrect JSON syntax.

Re: FMC 6.3 "unprocessable entity" error when trying to amend access rule

Michael Kozak — Thu, 09 Jan 2020 22:03:37 GMT

Can you post the JSON that you're sending in the PUT request? I've done this same process and from experience I can tell you that you can't just send back all the data that you got in the GET request. Specifically you have to remove the metadata and links attributes from the get result otherwise you will get this message.

Re: FMC 6.3 "unprocessable entity" error when trying to amend access rule

tyoung008 — Thu, 09 Jan 2020 23:23:08 GMT

For me, it was an ACP rule action set to BLOCK_WITH_RESET. I believe I copied that exactly form the API Explorer. I simply changed that to BLOCK and the error went away. I haven't re-tested it in a while.

Re: FMC 6.3 "unprocessable entity" error when trying to amend access rule

Oliver Kaiser — Sat, 07 Mar 2020 20:18:23 GMT

have you removed the metadata dictionary from the payload before executing PUT operation? That is the most common issue related to "Unprocessable Entity". If that is not it connect to FMC via SSH and execute "pigtail" command to get more details about the error from the webserver logs.

Re: FMC 6.3 "unprocessable entity" error when trying to amen

tyoung008 — Thu, 06 Oct 2022 15:32:15 GMT

Yes, I do not include the metadata dictionary when executing a put.

Thanks for the FMC info! I will check that out the next time I get the error.

Re: FMC 6.3 "unprocessable entity" error when trying to amend access rule

tylerjshannon — Thu, 04 Jun 2020 21:45:04 GMT

Other than the previously stated metadata and links keys, I have also run into issues with the urls key if you are using "urlCategoriesWithReputation" and also the users key if it references any AD realm.

I have this in all my scripts:

# Remove unprocessible entities  (i being an element of "items" from GET operation on the ACL/AccessRules)
i.pop("metadata")
i.pop("links")

if 'users' in i:
    for j in i['users']['objects']:
        j.pop('realm')                 # Need to remove the realm as it cannot be re-uploaded during PUT.

if 'urls' in i:                        # Need to remove invalid urlCategoriesWithReputation entries (missing name)
    if 'urlCategoriesWithReputation' in i['urls']:
        for index, j in enumerate(i['urls']['urlCategoriesWithReputation']):
            if 'name' not in j['category']:
                i['urls']['urlCategoriesWithReputation'].pop(index)

Here is an example of the FMC injecting a bunk category into my URL filtering which prevented my PUTs from working.

"urls": {
    "urlCategoriesWithReputation": [
        {
            "category": {                                               # This is a broken category
                "id": "89a91712-fe55-11e4-a157-a9da511cbd1e",           # It is missing "name"
                "type": "URLCategory"
            },
            "type": "UrlCategoryAndReputation"
        },
        {
            "category": {
                "name": "Abortion",                                     # This is a valid category.
                "id": "a774acd8-8240-11e0-9682-6814b504fd68",
                "type": "URLCategory"
            },
            "type": "UrlCategoryAndReputation"
        },
     ]
}

Re: FMC 6.3 "unprocessable entity" error when trying to amen

Jay_Work — Wed, 11 May 2022 16:06:39 GMT

Thank you so much - I kept getting a 422 response trying to modify variable sets on access rules and your response solved my problem (needed to remove the 'links' and both 'metadata' dictonaries). Been trying to figure this out for hours! Thanks again.

Re: FMC 6.3 "unprocessable entity" error when trying to amen

John Groetzinger — Wed, 11 May 2022 16:51:14 GMT

This is incredibly misleading because the swagger spec (the API explorer) is actually wrong for the "Example Value" for the requests. This has always been a problem. I will try to get this resolved in future releases, i have opened bug CSCwb85010 to address this (should be publicly visible in a day or two).

The problem is that the Example Value for the POST/PUT is actually the example response. One thing that may help is if you just ignore that example value, and click the "Model" instead (next to "Example value") which will tell you the valid structure for the request.