The Migration Mess: What to Fix in Your Spreadsheet Before You Open the HubSpot Import Tool

Most HubSpot migrations fail because of four spreadsheet problems: missing unique IDs, unplanned custom properties, unvalidated email lists, and unpruned legacy columns. Fix all four before you import a single row, and your onboarding call goes smoothly instead of turning into weeks of cleanup.

Your CRM migration is failing before it even starts.

We have watched this pattern repeat across dozens of onboarding calls this month. Teams move from spreadsheets, Airtable, or another CRM into HubSpot with genuine enthusiasm. They plan the timeline. They train their team. Then the import runs, and everything breaks.

The problem is not HubSpot. It is the data sitting in that spreadsheet.

Most failed migrations surface during the first onboarding call, before any automation turns on. By then, teams are already dealing with corrupted records, broken relationships between contacts and companies, and deliverability issues that stick around for months. The cleanup work that follows could have been prevented with a few hours of preparation.

Here is what tends to go wrong, and how to fix it before you import a single row.

1. No Consistent Unique ID Across Your Records

Your spreadsheet has contacts. It has companies. It has deals. But there is no reliable way to connect them.

This is the most common problem. Without a consistent unique identifier tying a contact to their company and that company to its deals, HubSpot cannot rebuild the relationships between records. Contacts end up orphaned. A contact exists, but HubSpot does not know which company they belong to. A deal exists, but it is not connected to the right owner.

The fix: before you export anything, set up a unique ID system.

For contacts, this might be an email address, if it is truly unique in your system. For companies, it could be a domain name or a custom ID you assign. For deals, it is typically a deal ID that links back to the company and contact.

Map these relationships in your spreadsheet with dedicated columns: Contact ID, Company ID, Deal ID. When HubSpot sees these relationships during import, it rebuilds them correctly.

If you are migrating from another CRM, export the unique IDs from that system and bring them along. They are your insurance against orphaned records.

2. Custom Properties Get Planned After Export, Not Before

You have exported your data. You are ready to import. Then someone asks where lead source information goes, or what field holds name pronunciation for your international team.

Now you are creating custom properties in HubSpot while the import sits in limbo or imports without those fields and spending weeks backfilling information that should have been there from day one.

The fix: plan your custom properties before you export.

Sit down with sales, marketing, and anyone else who uses the CRM. Ask what information you track that HubSpot does not have a native field for: name pronunciation, lead source, industry vertical, customer segment, preferred contact method. Document all of it.

Create those custom properties in HubSpot before you import and map your spreadsheet columns to them. When the import runs, the data lands in the right place immediately.

This takes an hour of planning and saves weeks of cleanup.

3. Contact and Email Lists Go in Unvalidated

You are importing 10,000 contacts. That sounds fine until 2,000 of them turn out to have invalid email addresses.

Typos, duplicates, fake addresses, and contacts with no email at all slip through when nobody validates the list before importing. Email deliverability takes the hit from day one: bounce rates climb, sender reputation drops, and inbox providers start filtering your messages.

The fix: validate your email list before you import.

Tools built for this, like ZeroBounce or NeverBounce, can check your contact list for you. Remove invalid addresses. Flag duplicates. Consolidate records where the same person shows up multiple times with slightly different emails.

Skipping this step is the difference between a healthy email program and one that is broken from the start.

4. Every Legacy Column Comes Along Instead of Getting Pruned

Your old spreadsheet has 150 columns. Some matter. Most do not.

Export all 150, import all 150, and HubSpot ends up cluttered with fields nobody uses. Your team gets confused about which fields matter. Your data model turns into a mess, and cleaning it up later means deleting fields while worrying about what depends on them.

The fix: audit your columns before you export them.

Ask whether you actually use each field, and whether anyone in HubSpot will need that information. If the answer is no, leave it behind. Keep only the fields that matter for reporting, sales workflows, or customer communication.

A focused data model is easier to understand, easier to maintain, and easier to build workflows around.

The Pre-Import Checklist

Work through this before you open the HubSpot import tool.

• Unique IDs: Do your contacts, companies, and deals have consistent, unique identifiers? Can you map the relationship between them?
• Custom properties: Have you identified every field HubSpot doesn't support natively and created those properties in HubSpot before importing?
• Email validation: Have you run your contact list through a validation tool? Are you confident in the quality of your email addresses?
• Column audit: Have you removed columns you do not need, so your export contains only the fields that matter?
• Duplicate check: Have you identified and consolidated duplicate records, so you have one source of truth for each contact and company?
• Data mapping: Have you mapped which spreadsheet columns go to which HubSpot fields? HubSpot's import documentation covers this process in detail.

Check all six boxes and your migration goes smoothly. Skip any of them, and you will be dealing with the consequences for months.

FAQs

Why do HubSpot migrations fail before onboarding even starts?

Most failures trace back to spreadsheet problems, not HubSpot itself: missing unique IDs, unplanned custom properties, unvalidated emails, and unpruned legacy columns. These surface during the first onboarding call because that is when the import runs against real data.

What unique ID should I use for contacts, companies, and deals before a HubSpot import?

Use an email address for contacts if it is truly unique, a domain name or custom ID for companies, and a deal ID that links back to both. Mapping these relationships in dedicated columns lets HubSpot rebuild them correctly on import.

Do I need to create custom properties in HubSpot before importing data?

Yes. Identify any information your team tracks that HubSpot does not have a native field for, such as lead source or industry vertical, and create those properties before you import. This prevents weeks of backfilling missing data afterward.

How do I validate an email list before a HubSpot migration?

Run your contact list through a validation tool like ZeroBounce or NeverBounce before importing. This removes invalid addresses and flags duplicates, protecting your deliverability and sender reputation from the start.

Should I import every column from my old spreadsheet into HubSpot?

No. Audit your columns first and keep only the fields your team uses for reporting, sales workflows, or customer communication. Importing every legacy column clutters your data model and makes cleanup harder later.

Why This Matters

A failed migration is not just a technical problem. It is a business problem. Your team loses confidence in the CRM. They spend time fixing data instead of selling. Reporting becomes unreliable, and automation does not work because the data underneath it is broken.

The good news: every one of these problems is preventable. They need a few hours of work before you import, not weeks of work after.

If you are planning a migration, start with the data. Validate it. Clean it. Organize it. Then import it into HubSpot.

Your onboarding call will go much better.

Planning a migration and want a second set of eyes on your data before you import? Talk to Concept's HubSpot onboarding team.