If your DigaPorter processes involve also converting AAC Audio files!

Step-by-step guide

DigaPorter is capable of handling the audio file formats .aac and .mp4
This is done be copying the decoder files into the program folder (usually a subdirectory of DigaSystem by the name of SAF) and registering the .ax files:

mc_dec_aac.dll
mc_dec_aac_ds.ax
mc_demux_mp4.dll
mc_demux_mp4_ds.ax
mc_enc_aac.dll
mc_mux_mp4.dll

When running DigaPorter on e.g. Windows Server 2008 R2 - this is not enough!
You may see error messages in DigaPorter logfiles;

Convert file error: Fehler bei der Initialisierung der Transformation (0x8011)

This is caused by a missing Server component.
You need to install the Microsoft components for Desktop Experience which is a feature and can be installed inside the Server Manager.
These components include the Media Foundation Framework which is essential for these conversions, elements that are included with Wokstation environments since Vista, but not necessarily with the Server OS's.

Afterwards an update for this feature must be applied.

See https://support.microsoft.com/en-us/kb/2483177

After a reboot, your audio conversion should work fine.