Error “There was an error converting the lead” on Lead Conversion in Salesforce

This article explains why Salesforce throws the error "There was an error converting the lead. Please try again. If the problem persists, please contact your administrator" during Lead conversion, and how to fix each cause. The following are a few reasons why the error might be thrown while converting the Lead.

Converting a Lead into an Existing Opportunity With a Different Currency

When a Lead is converted into an existing Opportunity, the currency field on the Opportunity record gets updated with the Lead currency. It is standard behavior that when a Product is associated with an Opportunity, the currency field cannot be changed. Hence, the user receives the error "There was an error converting the lead. Please try again. If the problem persists, please contact your administrator" if the Lead currency differs from the existing Opportunity currency that the user selected.

To fix the issue, update the Lead currency with the currency that is on the existing Opportunity which the user selected on the Lead conversion page in Lightning.

Custom Field Mapped to a Managed Package That Is Expired or Disabled

Lead conversion might fail when a custom field that is mapped to the Account or Contact object is part of a managed package that has either expired or is disabled. Check the packages installed in your org to find any that touch the Lead object, and check for any custom fields that are part of that package. Ensure those fields are not still being used for mapping if the package is expired or disabled.

Mismatch in a Mapped Picklist Field

This error occurs when there is a mismatch between the picklist values defined on the Lead and those on the target object in the Lead mapping settings.

For example, suppose the Lead has a picklist field labeled "Region" with a value of "Oregon", and this field is mapped to the "Region" picklist on the Account object. If the Account picklist does not include "Oregon" as a valid value, the system throws an error during conversion due to the discrepancy.

To resolve this, ensure that both picklist fields contain matching values or update the mapping accordingly.

Flow or Automation Error During Lead Conversion

To determine the root cause of the error, generate a debug log during the Lead conversion process. The debug log helps identify which automation or validation rule is failing.

For example, when converting the affected Lead, a Process Builder flow is triggered to create a new Opportunity. One of the actions attempts to relate an Opportunity Product to a Price Book that is marked as Inactive. This results in a failure during the conversion process.

Use the debug log to trace the execution path and confirm whether the inactive Price Book is causing the issue. For instructions on how to generate a debug log, refer to Debug Logs in Salesforce Help.