What is the FBK file format?
.fbk is a backup file associated with Microsoft Dynamics NAV, the ERP platform originally developed by Navision A/S and acquired by Microsoft in 2002. .fbk files store backup copies of .fdb native database files. The classic NAV native database runs an exclusive-access server, so all active client sessions must be disconnected before a backup can be created.
Microsoft Dynamics NAV is an ERP solution created by Microsoft. It covers the following business areas:
- Enterprise resource planning (ERP)
- Material requirements planning (MRP)
- Customer relationship management (CRM)
- Supply chain management (SCM)
- E-commerce / B2B integration
NAV now uses Microsoft SQL Server as the back-end data solution in most deployments, producing .bak backups instead of .fbk. However, native-database installations can still be backed up as .fbk files. The platform has since evolved into Dynamics 365 Business Central, which no longer uses this format.
An .fbk file must be restored using the NAV client's built-in restore function; it cannot be opened as a generic database file.
Security & safety
RISK: LOWAn .fbk NAV backup is inert data - it doesn't execute. The real concern is that it can contain sensitive business/financial data, so handle and store it securely and restore it only into an authorized NAV environment. Restoring requires a compatible NAV version and license; a mismatch fails rather than damaging anything. If the file is actually a Firebird/Kies/FoxPro backup, using the wrong tool simply won't work - verify the source first.
Format details
in a nutshell- Firebird database backup (gbak) - Firebird/InterBase databases are commonly backed up to .fbk via the gbak utility; restored with gbak/Firebird tools.
- Samsung Kies backup - Older Samsung Kies created .fbk phone backups (contacts, messages, settings) restored through Kies/Smart Switch.
- Visual FoxPro backup - Some FoxPro/legacy database tools used .fbk for backup copies of tables/databases.
Programs that open FBK files
Windows2 apps
Microsoft Dynamics NAV (client)
Paid Use the NAV client's File > Database > Restore (classic) to restore the .fbk into a NAV database. Requires a matching/compatible NAV version and a valid license (.flf).
Dynamics NAV partner / administrator
Paid If you don't run NAV, a Dynamics NAV/Business Central partner restores the backup for you - there's no generic 'open' for an .fbk. Technical details
deep spec| Developer | Microsoft (originally Navision A/S, Denmark) |
| Format type | Proprietary binary backup container |
| MIME type | application/octet-stream |
| Encoding | Binary |
| Magic bytes | No publicly documented fixed byte signature; identified by origin (produced exclusively by the NAV client Backup function) |
| Compression | Internal proprietary packaging applied by the NAV engine; not user-selectable or configurable |
| Encryption | None documented; security relies on file-system permissions and Windows server-level access controls |
| Typical file size | Tens of MB to several GB, depending on company data volume and number of included objects |
| Version compatibility | Must be restored into the same or a compatible Dynamics NAV version; cross-version restore is generally not supported |
| Backup scope | Can include selected companies, application objects (tables, reports, codeunits, forms), or a combination of both |
| Restore mechanism | NAV client built-in Backup/Restore function (File → Backup / File → Restore in the classic C/SIDE client) |
| Associated database file | `.fdb` - the Navision/NAV native database file that the `.fbk` backs up |
| Platform | Windows (Dynamics NAV client and native database server environment) |
| Superseded by | SQL Server `.bak` backups in SQL-hosted NAV deployments; Dynamics 365 Business Central uses a separate cloud-based export and backup model |
| Released | Navision Financials era (1990s); carried into Microsoft Dynamics NAV |
| Latest version | Used by the classic/native NAV database backup; superseded by SQL Server backups in later NAV/Business Central |
| Specification | learn.microsoft.com |
FBK conversions
Community Q&A
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