# Error when modifying multiple contacts with single-valued property with null value

**URL:** <https://community.hubspot.com/t/error-when-modifying-multiple-contacts-with-single-valued-property-with-null-value/128150>\
**Category:** APIs & Integrations\
**Tags:** python, developer-tools\
**Created:** [March 18, 2025, 7:26am UTC](https://community.hubspot.com/t/error-when-modifying-multiple-contacts-with-single-valued-property-with-null-value/128150 "2025-03-18T07:26:43Z")\
**Posts on this page:** 1\
**Showing post:** 9

<div class="post-metadata">

**Author:** ![evaldas](https://d10pqhm3lwygmk.cloudfront.net/user_avatar/community.hubspot.com/evaldas/32/69160_2.png) [@evaldas](https://community.hubspot.com/u/evaldas)\
**Post date:** [March 25, 2025, 2:28pm UTC](https://community.hubspot.com/t/error-when-modifying-multiple-contacts-with-single-valued-property-with-null-value/128150/9 "2025-03-25T14:28:11Z")

</div>

Hi @JMoleroAlonso,

As I had mentioned in previous messages, you cannot set the field as “unique value” if there is a change that field values will be the same.

To illustrate, this is NOT unique because values for “subscription\_\_monthly” are identical:

```lia-code-sample
{ ‘id’:‘record1’, ‘subscription__monthly’: ''}
{ ‘id’:‘record2’, ‘subscription__monthly’: ''}

```

To resolve this issue you have two options:

**Option A:** Change your unique value to a field that will ALWAYS have unique values, such as “id” or “email” - **this will allow passing null values in “subscription\_\_monthly” field**

**Option B:** If you are required to have “subscription\_\_monthly” as the unique value, make sure your “subscription\_\_monthly” field always has unique values. Example of option B:

```lia-code-sample
{ ‘id’:‘record1’, ‘subscription__monthly’: 'null_1'}
{ ‘id’:‘record2’, ‘subscription__monthly’: 'null_2'}

```

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_[View the full topic](https://community.hubspot.com/t/error-when-modifying-multiple-contacts-with-single-valued-property-with-null-value/128150)._