Decompile Your Microsoft Access Database to Improve Performance, Fix
Corruption, and Avoid Strange VBA Errors
Provided by: Luke Chung, FMS President
VBA Code Corruption and Performance Drag
Periodically, Microsoft Access databases with VBA module code perform
oddly. Code that previously worked suddenly fail or behaves incorrectly.
Here are some examples of errors that come up:
The database cannot be opened because the VBA
project contained in it cannot be read.
Error accessing file. Network connection may have
This error is particularly confusing if your file is
local and not on the network:
Compile Error: Out of Memory
It's all very confusing, especially when Compact and Repair does not
The initial assumption is that the database is corrupt, which is partially
true. People then resort to creating a new database and importing their
objects into it which is time consuming and a pain. It solves the problem,
but there's a better alternative to check first.
The Microsoft Access /decompile command
Fortunately, Microsoft Access offers a way to fix the VBA compiled state
with the /decompile command line option. The Compact and Repair feature only
applies to the tables and does not impact VBA code. The decompile command
When Access is started with this and you open your database, it discards all
the old VBA compilations, and leaves just your VBA source code. You'll need
to compile again to get the compiled state. After compacting, your database
may be significantly smaller.
To decompile your database, follow these steps
From the Windows, Start, Run command line, type: msaccess.exe /decompile
where msaccess.exe includes the complete path. For example, for Access 2016:
C:\Program Files\Microsoft Office\Office16\MSACCESS.EXE /decompile
From Access open the database you want to decompile (with trusted
authority for Access 2003 or later)
Open up any module. Compile it via Debug, Compile.., then File, Save.
Go back to the database and Compact it. The location of the
command varies by Access version.
The database size should be reduced and the strange errors related to the
VBA code should be gone.
The example above is for Microsoft Access 2016, but it also applies to
Microsoft Access 2013, 2010, 2007. 2003, 2002, 2000, 97 and earlier.
Create a Shortcut
To simplify doing this in the future (and you'll likely need this again),
create a shortcut on your Windows desktop pointing to where your copy of
Access is located:
Then, whenever your database is acting oddly, you can easily launch the
decompile version of Access to open your database and decompile it. In a few
minutes, you're back up and running with a smaller database.
Additional Resources and Technical Papers
Microsoft Access Database Administrator Products
Schedule and Automate Database Compacts
Total Visual Agent manages an unlimited number of databases across your network and
schedule database chores in the middle of the night. Perform
compact, backups, data extracts, running macros, command lines, and
other tasks. Schedule events hourly, daily, weekly, monthly or just
one time. Complete audit trail with email notification if anything
goes wrong. Free Demo
Monitor Your Database in Real-Time
Total Access Admin lets you monitor
Access databases in real-time to see who's currently in it and when
they leave. It flags users who disconnect in a suspect manner which
may indicate a source of database corruption. It can also perform
tasks after everyone has exited such as compact.