Salesforce Error 'Body Data Value too large' After Limit is Raised on the Length of Rich and Long Text Areas

Understanding Field Character Limits

After the limit has been increased for Long Text Area in Salesforce, it does not automatically impact all Long Text Area and Rich Text Area fields within the environment. This change allows an increase to the field's length manually from the default value to the new limit.   

An object can contain unlimited rich text area and long text area fields, although each edition’s limit for total custom fields allowed on an object, regardless of field type, applies. Each object can contain 1,638,400 characters across long text area and rich text area fields. When creating a long text area or rich text area field, set a character limit for the field—the maximum length of the text that can be entered. The default character limit for long text area and rich text area fields is 32,768 (32 KB). The maximum character limit for long text area and rich text area fields is 131,072 (128 KB). The minimum character limit is 256. This applies to custom fields only.

Steps to Increase the Field Limit

In Salesforce Classic
 

1. Navigate to Setup | Customize
2. Select the object. 
3. Click Fields.
4. Click Edit next to the field with the 'Rich Text Area' or 'Long Text Area' data type under the object's Custom Fields & Relationships related list.
5. Update the value on the Length field from the default value to the new limit value. 
6. Click Save.

1. Navigate to Setup | Create | Objects
2. Select the object.
3. Go to Custom Fields & Relationships related list.
4. Click Edit next to the field with the 'Rich Text Area' or 'Long Text Area' data type.
5. Update the value on the Length field from the default value to the new limit value. 
6. Click Save.

In Lightning Experience

1. Click Setup (Gear icon)
2. Click Object Manager
3. Select the Object Name
4. Click Fields & Relationships
5. Click Edit next to the field with the 'Rich Text Area' or 'Long Text Area' data type.
6. Update the value on the Length field from the default value to the new limit value.
7. Click Save.

Important Note:

This procedure applies to custom fields only. Standard Long Text Area fields cannot have their character limit increased. Each affected field must be updated individually — this change does not apply in bulk."

Idea Exchange link: 
Increase the character limit on Standard Long Text Area Fields