Long numbers, leading zeros, and dates get converted automatically, often without an error message to warn you.
Most problems are prevented at the import step, not fixed after the fact, by choosing Text as the column type before the data loads.
Get Data (Power Query) and the legacy Text Import Wizard both let you set column types before anything gets rewritten.

Common CSV Import Errors in Excel

Every spreadsheet person has hit this moment. You open a clean export and the product codes have turned into 1.23E+11. Zip codes lost their leading zero. Dates that were fine in the source system now read as the wrong day entirely.

None of this happens because your file is broken. It happens because the import step guesses a data type for every column, favoring numbers and dates over plain text. Once you know where those guesses go wrong, each error has a quick, repeatable fix.

Below are the errors that show up most often, why they happen, and how to stop them before your data gets corrupted.

Before You Import: A Prep Checklist

A few minutes of prep prevents most of the errors below and helps your file import go correctly on the first try.

Confirm the file is saved as UTF-8, especially if it came from a non-Windows system or another country's software.
Identify any columns with IDs, codes, phone numbers, or zip codes that start with zero or run longer than 15 digits.
Check whether the file uses commas or semicolons as the delimiter.
Open the file once in a plain text editor to spot obvious issues before anything gets converted.

Prep step	Why it matters
Confirm UTF-8 encoding	Prevents garbled characters (mojibake) on import
Flag ID-like columns	Lets you force Text type before Number gets guessed
Check the delimiter	Stops every entry from landing in a single column
Preview in plain text	Reveals stray commas, quotes, or blank lines early

Lost Leading Zeros

Symptom

Zip codes, employee IDs, or product codes like 00123 turn into 123 the moment the file opens.

Cause

The default General type treats any all-digit value as a number, and numbers do not store leading zeros.

Fix

Open the Data tab and select Get Data, then From Text/CSV.
In the preview window, choose Transform Data to open Power Query.
Select the affected column and set its Data Type to Text.
Load the data. The leading zeros are preserved as typed characters.

Best for: any column of codes or IDs, not just zip codes.

Long Numbers Turned Into Scientific Notation

Symptom

A 12-digit tracking number or barcode shows up as 8.7986E+11 instead of the original digits.

Cause

The default General type displays numbers over 11 significant digits in scientific notation, and numbers past 15 digits are permanently truncated, with the extra digits replaced by zeros.

Fix

Do not double-click the file to open it directly.
Use Data, then From Text/CSV, or the legacy Text Import Wizard.
In Power Query, set Column Data Type to Text before loading, or in the wizard, mark the column type as Text in step 3.
Load the file. The full number now imports as a text string.

Best for: barcodes, tracking numbers, account numbers, and any ID over 11 digits.

Caution: if a number has already been opened and saved once, digits past position 15 are gone for good. There is no formula fix. Always import from the original source file as Text.

Wrong Date Format

Symptom

A date meant to read July 9, 2026 shows up as September 7. Or it shows up as a raw serial number like 46216.

Cause

Dates follow your system's regional settings on import. A source using day/month/year gets misread if your default is month/day/year, or the other way around.

Fix

Import through Data, From Text/CSV, and open the Power Query editor.
Select the date column and set Data Type to Date, choosing the correct locale under Data Type Detection if the reading is ambiguous.
Alternatively, in the legacy Text Import Wizard, select the column and set it explicitly to DMY, MDY, or YMD to match the source.
Load the data and confirm a few entries against the original file.

Best for: any file coming from a system outside your own country or region.

Garbled Characters and Encoding Errors

Symptom

Names or special characters display as strange symbols, such as "JosÃ©" instead of "José."

Cause

The source file was saved in one character encoding, often Windows-1252, but it gets read as another, usually UTF-8, so the byte values are interpreted with the wrong character map.

Fix

Use Data, From Text/CSV rather than double-clicking the file.
In the import preview, change File Origin to match the file's actual encoding, or set it to UTF-8 if that's what the source used.
If characters still look wrong, reopen the original file in a plain text editor and re-save it explicitly as UTF-8 before importing again.
Watch for a byte order mark at the very start of the file. It can corrupt the first column name if left unstripped.

Best for: files exported from non-English systems or older databases.

Delimiter Mismatches

Symptom

An entire line lands in a single column instead of splitting into separate fields.

Cause

The file uses a different separator than expected, most often a semicolon instead of a comma, which is common in files exported from European regional settings.

Fix

Open Data, then From Text/CSV, and check the Delimiter dropdown in the preview window.
Change it from Comma to Semicolon, Tab, or Custom as needed.
If the file mixes delimiters inconsistently, use Find and Replace in a plain text editor first to standardize on one delimiter.
Reload the file once the delimiter is corrected.

Best for: files shared internationally or exported from non-US software.

Mismatched or Missing Column Headers

Symptom

Import fails outright, or every column lands one position off from where it should be.

Cause

The top row is missing, contains extra spaces, has a different count than the data below it, or was disrupted by merged cells left over from earlier editing.

Fix

Add a clean header row if one is missing. Give every column a label and leave no cells blank.
Remove any extra spaces before or after each column name.
Check for and unmerge any merged cells if the file was previously edited.
Re-save and re-import once the top row is clean.

Best for: files that have been passed through several tools or manually edited before reaching Excel.

Regional Number Format Mismatches

Symptom

A value like 1.234,56 imports as a huge whole number or throws an error, instead of reading as one thousand two hundred thirty four point five six.

Cause

Different regions swap the roles of the comma and the period. Import settings apply your system's regional defaults, which can conflict with how the source file was structured.

Fix

In the Text Import Wizard, click Advanced on the final step.
Set the decimal separator and thousands separator to match the source file, not your system default.
In Power Query, set the column's locale under Data Type Detection to match the file's country of origin.
Confirm a few sample values against the original file before trusting the result.

Best for: financial or pricing data from international sources.

File Size and Row Limit Errors

Symptom

The import stalls, the program freezes, or you see a warning that the file is too large to open.

Cause

Excel supports up to 1,048,576 rows and 16,384 columns per worksheet. A file with more rows than that, or one that is simply very large, can slow things down or fail to load completely.

Fix

Check the file's record count in a text editor, or with a quick Power Query preview before opening it in a worksheet.
Split large exports into smaller files by date range, region, or another logical column before importing.
Use Power Query rather than a direct open. It streams large files more efficiently than the default open command.
Remove unused columns or blank entries in the source to shrink the count before you import.

Best for: exports from databases, CRMs, or analytics tools with a large record count.

Common CSV Import Issues at a Glance

Error	Root Cause	Fix
Lost leading zeros	Digits treated as a Number	Import column as Text
Scientific notation	Limit past 11 to 15 digits	Import as Text, avoid direct open
Wrong date reading	Regional mismatch	Set locale explicitly
Garbled characters	Wrong encoding assumed	Set File Origin to UTF-8
Data in one column	Wrong delimiter detected	Change delimiter in import preview
Columns shifted	Missing or dirty header row	Clean up column names before import
Wrong decimal values	Regional separator mismatch	Set decimal and thousands separator
Import stalls or fails	File exceeds row or size limit	Split file, use Power Query

CSV Import Troubleshooting: Common Mistakes

Double-clicking the file to open it: skips every safeguard. Use Data, From Text/CSV instead.
Trusting the auto-detected column type: always review the preview window before clicking Load or Finish.
Editing and re-saving a corrupted file: if digits past 15 are already truncated, they cannot be recovered. Re-import from the original source.
Ignoring the file origin encoding setting: it is easy to miss and is the single most common cause of garbled text.
Skipping a final spot-check: compare a handful of entries against the source file after every import.

After Your Excel File Is Ready

Most CSV issues come from formatting inconsistencies. After fixing these errors, Wauld's CSV importer makes certificate issuance straightforward.

Preparing your spreadsheet is only the first step. If you're creating certificates for employees, students, event attendees, or training participants, you'll eventually need to generate and distribute those credentials.

With Wauld, you can:

Upload a CSV file in minutes
Generate thousands of personalized certificates or badges
Automatically populate names, dates, IDs, and other dynamic fields
Add QR-code verification
Email credentials to recipients automatically
Track opens, downloads, and shares from a single dashboard

Instead of manually creating certificates one by one after preparing your Excel sheet, you can automate the entire issuance workflow.

Once your recipient list is clean, see how Wauld's online certificate maker turns an upload into finished, verifiable certificates. If your recipient names still need cleanup, this guide on how to combine first and last names in Excel covers that step before you export. And if your data starts as form responses, check the Microsoft Forms to Wauld workflow.