Troubleshooting

Common problems with clear fixes. If your issue isn't here, check the FAQ or contact support with your job ID.

Upload problems

"File format not supported"

Cause: file extension isn't one of CSV, TSV, XLSX, XLS, pipe-delimited.

Fix: save the file as one of the accepted formats. For Google Sheets, File → Download → CSV/XLSX. See Supported file formats.

"File exceeds your tier's size limit"

Cause: file is too big for your plan (10 MB on Free, 50 MB on Starter, 250 MB on Pro, 1 GB on Business).

Fix: upgrade your plan, OR split the file into multiple smaller files and run multiple matches. If upgrading, see Upgrading and downgrading.

"Macro-enabled Excel files are blocked"

Cause: you uploaded a .xlsm or .xlsb file (macros present — security risk).

Fix: open in Excel, Save As .xlsx. This strips macros. Re-upload.

"File appears to be corrupted"

Cause: the file's encoding or structure can't be parsed.

Fix: open in Excel or a text editor to confirm the file is valid. If it opens cleanly there but fails here, encoding detection may have failed — re-save as UTF-8. For CSVs, check for inconsistent row lengths or unescaped special characters.

"Encoding detection was uncertain"

Cause: the file's encoding was hard to detect automatically.

Fix: usually a warning, not a block. Verify matching output looks right. If not, re-upload with the explicit encoding (dropdown on upload screen). Most common correct answer for Excel-exported CSVs: Windows-1252.

Column detection problems

Account numbers lost leading zeros

Cause: column was detected as "number" instead of "identifier".

Fix: on the Upload step, click the column's type badge and change it to "identifier". Leading zeros are preserved.

Dates displayed wrong

Cause: date format was ambiguous (03/04/2026 — March 4th or April 3rd?) and the Genie defaulted to US.

Fix: on the column's type settings, change Date Format → European (DD/MM/YYYY) or specify explicitly.

Column detected as "free text" but it's an email

Cause: values have formatting issues (extra whitespace, quotes, duplicated domain) that broke email detection.

Fix: override the column type to "email" manually. Cleansing will then apply email-specific rules (lowercase, trim).

Email column has 30% malformed addresses

Cause: data quality issue. Your file has bad emails.

Fix: either drop those rows before matching (the cleansing report shows you which), or accept that those rows will be unmatched.

Match quality problems

Low match rate

Multiple causes, checked in order:

Wrong profile. Confirm you chose Person for people, Company for orgs, etc. See Choosing a profile.
Threshold too strict. Lower from 70 → 60, re-run. If match rate jumps, your threshold was the bottleneck.
Master doesn't contain the records. If your source is genuinely new-to-you leads, a low match rate is correct.
Identity columns sparse. Check the column profile — if email/phone/name have high null rates, signal is weak.
Cross-file column mismatch. Verify field mapping is correct.

See Setting the confidence threshold for the iterate workflow.

Huge review queue

Cause: threshold is in the high-density part of the score distribution.

Fix: look at the score distribution chart. Raise the threshold to the low-density gap above the current one. Reduces review workload by pushing borderline cases to unmatched.

Obvious wrong matches in results

Cause: your threshold is too low, OR your profile is comparing the wrong fields.

Fix: inspect a few sample matches side-by-side. If the cases are "obvious same person, different email" — threshold is correct. If they're "different people, similar names" — raise threshold. If they're "totally unrelated" — wrong profile.

Matches missing that should be obvious

Cause: usually case mismatch, formatting difference, or a column being compared that shouldn't be.

Fix:

Pick a specific row you expect to match and find it in both files
Look at every comparable column — what differs?
If the difference is formatting (case, whitespace, punctuation), cleansing should have handled it. Check the cleansing report.
If the difference is meaningful (different address, different phone), that's why matching failed — you need looser comparison on that field.

Same person matching multiple master rows

Cause: your master file has duplicates.

Fix: run a dedupe pass on the master first. Then re-run the match.

Two source rows both matching the same master

Cause: by default, this is allowed (one-to-many matching).

Fix: if you need unique matches, enable one-to-one matching on the Configure step.

Performance problems

Match job seems stuck

Check:

Job status on the Jobs list page — processing means it's still running
Progress bar on the Run step — if it's still moving, it's still working
Elapsed time — matching 500k source rows against 1M master rows takes minutes, not seconds

If truly stuck (no progress for 30+ min):

Note the job ID
Cancel the job (top-right of the Run step)
Contact support with the job ID; we'll investigate

Upload is slow

Causes:

File is large (multi-GB takes minutes)
Column profiling on 500k+ rows takes 30–60 seconds
Network upload speed constrained (the file has to reach S3)

Fix: be patient. If it takes >5 min on a <100 MB file, refresh; if the upload dropped, retry.

Dev tools shows many requests

Normal: the app uses SSE (server-sent events) for live progress. Each progress tick is a separate event. Not a problem.

Export problems

CSV opens in Excel with all data in one column

Cause: Excel isn't detecting the comma delimiter.

Fix: open a new blank Excel workbook first, then Data → From Text/CSV → select the file. Specify comma as delimiter. Or use .xlsx export directly from ListMatchGenie.

CSV shows `'=...` in cells

Cause: CSV injection protection escaped formula-prefix characters.

Fix: this is by design — the leading apostrophe prevents formula execution on opening. In Excel/Sheets, the apostrophe is invisible in normal display. If you need the literal formula behavior, edit the cell and delete the apostrophe. See CSV injection protection.

You're on the wrong plan (Team requires Business)
You're at the seat cap (5 seats)
The email is already associated with an account (they need to sign in with existing credentials)

Fix: upgrade to Business, remove an inactive member, or have the invitee use their existing account.

Cause: invitation link expired (14-day window).

Fix: re-issue the invitation from the Team page.

Contacting support

If your problem isn't covered here:

Starter and up: email support with your account email and a description of the problem
Pro and up: include your job ID (visible on Jobs page) for fastest triage
Business: priority support, typically response within 4 business hours

Email: support@listmatchgenie.com

FAQ — common questions
Glossary — term definitions
PII and security — for security-specific questions