How to Reconcile a Portfolio Tracker After a Failed API Sync

05 November 2026

A failed API sync leaves your portfolio tracker with missing or stale data. The fix is to identify what the sync actually imported, manually fill the gap using export files, and then flag the broken API connection so the tracker does not overwrite your corrections later.

What a failed API sync actually does

When an API connection fails mid-sync, the tracker may have imported some transactions and stopped, imported none, or imported duplicates from a previous partial sync. You cannot trust the balance or the transaction list until you confirm what landed.

Most trackers log the last successful sync timestamp. Check that first. If the timestamp is recent but the balance is wrong, the sync likely imported partial data. If the timestamp is old, the sync failed entirely and nothing changed.

Step 1: Check what the tracker shows

Open the transaction history for the affected wallet or exchange. Sort by date. Look for:

• A gap in dates around the time of the failed sync
• A sudden jump or drop in balance that does not match your records
• Duplicate transactions with identical timestamps and amounts

If you see duplicates, refer to the site’s article on duplicate transaction import inflating portfolio balance. That is a separate problem, but it often follows a failed sync.

Step 2: Export fresh data from the source

Do not rely on the tracker’s cached data. Go directly to the exchange or wallet and export a CSV or similar file for the period the sync missed.

For exchanges, use the transaction history export, not the trade history export. Transaction history includes deposits, withdrawals, and fees. Trade history often omits non-trade movements.

For wallets, use the block explorer or wallet software to export by address. If the wallet supports watch-only import, that method preserves the original transaction IDs and avoids re-entering data manually.

Step 3: Compare and identify the missing records

Open the tracker’s existing transactions and the new export side by side. Match on:

• Transaction ID (TXID) if the tracker stores it
• Date and time to the minute
• Amount and asset

Any record in the export that does not appear in the tracker is missing. Any record in the tracker that does not appear in the export is either a duplicate from a prior import or a transaction that was already there before the failed sync.

Step 4: Import the missing records manually

Use the tracker’s manual import or CSV upload feature. Do not re-run the API sync until you have confirmed the connection is stable.

When importing, watch for column mismatches. The export format may differ from what the tracker expects. The site has an article on fixing CSV import column mismatches in crypto tax software; the same principles apply here.

If the tracker allows you to tag imported records as “manual” or “API”, tag them as manual. That way you can distinguish them from future API imports.

Step 5: Reconcile the balance

After the import, compare the tracker’s balance to the source balance again. If they match, the reconciliation is complete for that source. If they still differ, one of the following is likely:

• The tracker counts pending or unconfirmed transactions differently
• The export omitted a fee or rebate that the API normally includes
• A transaction was imported twice and needs to be deleted

Check pending transactions first. Many trackers show unconfirmed transactions with a different status. If the source shows a confirmed balance but the tracker shows a pending balance, the sync may have imported a transaction that later confirmed but the tracker did not update.

Step 6: Disable or flag the broken API connection

A failing API will corrupt the data again if it runs. Most trackers let you pause or delete a connection. Do that. If you want to keep the connection for future use, set it to manual sync only and check the result each time.

Some exchanges revoke API keys after repeated failures. If you keep retrying a broken key, you may lose access and need to generate a new one. That means re-authenticating and possibly re-importing history.

When to rebuild from scratch

If the API failed repeatedly and you cannot tell which transactions are real, the cleanest fix is to delete the affected portfolio, re-export the full history from the source, and re-import everything in one batch. This is time-consuming but eliminates the risk of hidden duplicates or gaps.

Before deleting, export the tracker’s current data as a backup. If the re-import misses something, you can compare the backup to the fresh import.

Preventing the same problem

• Test API connections after any exchange maintenance or credential change
• Keep exports of your full transaction history at least quarterly
• Use a tracker that logs every sync attempt with a status code
• Do not let the tracker auto-sync daily if you rarely check the results

A failed sync is not data loss. It is a gap in data transfer. The steps above close the gap without trusting the API to do it correctly next time.

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