"We can't display this page." Error on the Map Lead Fields Screen After Deleting a Mapped Custom Field

This article explains why the "We can't display this page" error appears on the Map Lead Fields screen, and how to fix it when it's caused by a deleted mapped custom field.

Why This Error Occurs

This error occurs when a custom field associated with Lead Conversion field mapping is deleted before its mapping is removed. Deleting a mapped field while the mapping still references it leaves the Lead Conversion configuration in an inconsistent state, which causes the Map Lead Fields screen to fail to load.

Identify and Restore the Deleted Field

1. Navigate to Setup > Object Manager and check the Fields & Relationships for the four related objects: Lead, Account, Contact, and Opportunity.

2. Click Deleted Fields at the top right of the screen to check for any recently deleted fields.

3. If you find the relevant field, click Undelete.

Remove the Field Mapping

1. Navigate to Setup > Object Manager > Lead > Fields & Relationships.

2. Click the Map Lead Fields button. (Restoring the field in the previous step allows this page to open without the error.)

3. Locate the mapping related to the restored field and clear or remove it.

Re-delete the Field

Once the mapping has been successfully removed, you may delete the custom field again if it is no longer needed.