The default maximum size limit for an attachment file that can be added to a record in the ServiceNow platform is 1024 MB for a new out-of-box instance. However, this limit can be adjusted in the system to allow for larger maximum attachment sizes or decrease the maximum size of an attachment allowed on the system.
If a user does exceed the currently set limit for the maximum attachment size for a specific attachment, the attachment will not be uploaded to the instance and the following error message will be displayed, indicating that the attachment was not added to the record:
Large attachments can sometimes cause performance issues on the system and unnecessarily bloat the size of the database, and thus some customers may opt to decrease the maximum allowable size of a specific file attachment. Alternatively, customers may find, that for their business, the current setting (by default 1024 MB) is not large enough and need to increase this size. This article will describe the method by which this size limit can be adjusted.
The following procedures can be used to change the maximum allowable size for an attachment uploaded to the system.
Login to the instance with an account having admin rights to the instance.
Using the Menu Navigator, browse to the following location on the instance: System Properties -> Security.
The Security Properties Page for the instance will appear. Locate the property on the page with the heading "Maximum file attachment size in megabytes". Below this heading is a field in which the specified value can be typed to specify the number in MB of the maximum allowable attachment size. Thus, attachments that are smaller or equal to this number can be uploaded to a record with no issues, but any value larger than this value will generate an error dialog box message and will be refused upload to the system.
Once a valid value has been typed in the field, click the Save button on the Security Properties form. A Save button is found at both the top and bottom of the page. The change will be reflected immediately on the instance.
If the field is left blank (no value) the system specified limit (currently set at 1 GB) will be used as the maximum uploaded attachment file size.
Note that this value is actually stored as a System Properties (sys_properties) record on the instance. Thus, an alternative method of modifying this value would be to open the sys_property record with the name com.glide.attachment.max_size directly, adjusting the value as needed and saving the property record.
Also note that the email system has it's own system properties that govern the maximum size limit for files as attached to emails. However, the global setting (as described in this article) will override the setting specific to the email system if this global setting is lower than that given for the email system.
On the user end, providing that .zip files are enabled as attachment file types, compressing a file can often help drastically decrease the size of a file before being added to a record on the system. This should often help bring the total size of the download below the maximum size as specified on the instance.