Guide

How to fix corrupted Excel files

When Excel refuses to open a workbook, it usually means the underlying file structure broke during a save, transfer, or sync. This guide covers why corruption happens, safe steps to take before repair, and how FixFileFast reconstructs damaged spreadsheets without guessing at your data.

Common causes of Excel corruption

Modern Excel files (.xlsx) are zipped collections of XML documents. If the ZIP container is truncated or if one XML part is damaged, the entire workbook may fail to load. Common causes include saving to a network drive during an outage, an interrupted autosave to cloud storage, or abrupt shutdowns that leave the workbook half-written.

Older .xls files can also be corrupted when macros misbehave or when a workbook is opened in incompatible software. Large pivot tables, external data connections, or unsupported add-ins can increase the odds of a file being marked as invalid by Excel.

Safe pre-repair checklist

Duplicate the file. Work on a copy so you preserve the original binary data.
Check storage sync. If the file is in OneDrive, Google Drive, or Dropbox, download the most recent version instead of opening it directly from the sync folder.
Open with protection. Excel’s “Open and Repair” feature can sometimes fix minor XML errors, but avoid saving over the original if it opens only partially.
Inspect file size. If the file is dramatically smaller than expected, corruption may be severe. In that case, look for backups before attempting aggressive edits.

How FixFileFast repairs spreadsheets

FixFileFast focuses on preserving the workbook’s data layer. When you upload a file with the Fix a File tool, it inspects the XLSX container, validates XML parts, and identifies which sheets, shared strings, and styles are usable. If parts are corrupted, FixFileFast reconstructs a clean workbook by extracting the healthy components and rebuilding a consistent structure.

For Excel-to-CSV workflows, FixFileFast can also convert each sheet into clean CSV files, which means you can recover data even if the original formatting is beyond repair. The system also generates a SQL-ready schema so your recovered data can be imported into a database without manual cleanup.

What cannot be recovered

Corruption that destroys the raw data cells cannot be reconstructed. If a worksheet XML part is missing entirely, the tool can only recover what remains in other sheets. Complex formatting, macros, or external links may be lost if their referenced components are damaged. In those cases, focus on preserving the data first, then reapply formatting later.

Encrypted workbooks require the correct password. FixFileFast does not bypass encryption; it can only operate on files that are already unlocked or provided with valid credentials.

Privacy and handling notes

FixFileFast processes spreadsheets to perform the repair and does not sell or reuse your data for advertising. For sensitive financial or HR sheets, consider removing irrelevant columns before upload and review our Privacy Policy for data retention details and third-party service disclosures.

FAQ

Can FixFileFast recover formulas? When formulas are intact in the XML, they are preserved. If the formula part is corrupted, the output focuses on data values.

Will charts and pivots be restored? Charts and pivots rely on multiple files inside the workbook. If those files are missing, the recovered workbook may omit those elements.

Is CSV export safer than Excel repair? CSV export is a good fallback for data recovery because it avoids complex formatting and macros. You can always rebuild structure later.

How long does repair take? Most files complete within minutes. Extremely large workbooks or advanced repair modes may take longer.

Related resources

Need to repair a damaged PDF instead? See Fix corrupted PDF. If you are unsure whether to attempt recovery or repair, read File recovery vs repair.