Symptoms

Unable to upload MIB file in "SNMP MIBs". The documentation says a file must be uploaded without a file extension, but when I try to do so I get a prohibited file type error.  

Release

All Versions

Cause

The system property glide.ui.strict_content_types  which is restricting to load only the selective files into the instance                       
https://docs.servicenow.com/csh?topicname=restrict-file-extensions.html&version=latest 

In the instance, we have a certain list of values and hence a file without an extension is not allowed to upload into the system 

Resolution

To upload SNMP MIB file,

1. Save your file as ".txt" extension

2. Add "txt" in the "glide.attachment.extensions" property if not available

3. Follow the steps

    a) Navigate to MID Server > SNMP MIBs.

    b) Click New to create a new record.
        The MID Server MIB File form opens to create a new ecc_agent_mib record.

    c) Use the following information to fill out the form:

             Name: The name of the MIB.
             Version: The version of the MIB.
             Source: Use this field to note where the MIB was acquired, such as a URL.
             Description: The description that appears in the ecc_agent_mib table.
             Active: This check box denotes whether the MIB module is enabled or disabled in the instance.

    d) Click the Add Attachment icon (attachment icon) in the upper right to attach the actual MIB file to the new record.

The MIB name must begin with an alphabetical character.
Remaining characters must be one of the following: alphanumeric, hyphen ( - ), or underscore ( _ ).
The file name must not have an extension. You can reference the existing MIBs for examples. Use the actual name of the MIB for both the MIB record name and the attachment name, but it is not required.

4. Now, upload the "FILE_NAME.txt" extension file to the SNMP MIB file

5. Do an update on the MIB file record so that the extensions will be cleared out using business rule "MIB filename compliance"

Business Rule Name: MIB filename compliance
/nav_to.do?uri=sys_script.do?sys_id=b7b95305ef11210003d778f775c0fb34

Additional Information

Please refer to docs below

https://docs.servicenow.com/csh?topicname=t_LoadAMIBModule.html&version=latest