Error "An unexpected error has occurred while opening the workflow. See the event log on the AOS and contact your system administrator to resolve the issue" on creating the workflow.

To resolve mentioned error we have following options.

Solution 1:
Do incremental CIL compile.

Not succeeded?!

Solution 2:
Do full CIL compile.

Still not succeeded?!

Solution 3:

Stop AOS service.

Rename XppIL folder to XppIL_old. form the following location.
<Drive letter>:\Program Files\Microsoft Dynamics AX\60\Server\<Instance Name>\bin

Start AOS service.

Do full CIL compilation.

Now your face should be filled with SMILE :)

Have any question?! Please comment.