Siemens Industry Online Support
Siemens AG
Entry type: FAQ Entry ID: 10208766, Entry date: 10/19/2007

How do you clear message 256:26 "An OLE error has occurred"?

  • Entry
  • Associated product(s)

The message "An OLE error has occurred" can be displayed, for example, when opening blocks or starting functions STEP 7 or the options packages if the start of a Windows application has failed.

OLE (Object Link Embedding) is a central Windows mechanism that is used internally when starting applications.

This error can have very different causes, e.g. incorrect installation or incorrect registry entries or even corrupt files in the Windows system.

The table below describes a number of causes and remedies for these messages.

No. Causes and remedies for internal OLE errors
1 There is not enough space on the hard disk. The database cannot be started.

Create free space on the hard disk (>100MB) and set the virtual main memory to user-defined (information on this is available in the STEP 7 readme file). More information on setting the virtual memory is available in our Entry:

  • "How do you make the settings for the virtual memory in MS Windows XP/2000/ME/NT/9x?" Entry ID: 20440472.
2 Check whether the internal STEP 7 database was started when the PC was booted and also the function Start/stop server in the SIMATIC workstation. For this, in Windows you open the dialog "Start > SIMATIC > STEP 7 > Configure SIMATIC workstation". In order to be able to start the internal STEP 7 database, the following entries must be available and executed in the autoexec.bat in Win95/98:
  • SET SQLANY=C:\SIEMENS\common\Sqlany
3 Incorrect DLL in Windows/System and/or incorrect registry entries:
In the Explorer you start the program editor "c:\siemens\step7\ska\s7kafapx.exe" and evaluate the error message. If the following message appears:
  • "The file S7HRVERX.DLL is linked with the missing export S7OTBLDX.DLL: s7_set_password",

then please check whether the file "S7OTBLDX.DLL" is in the Windows system directory. When using STEP 7 V4.02, this file must be deleted from the Windows system directory. If the following message is displayed:

  • "The file S7KAFAPX is linked with the missing export OT5050R.DLL:4224",

then please check whether the file "OT5050R 2x " is on the computer. Change the names of all the files except those in the S7BIN directory.

4 WIN 95a or b: when WINDOWS was installed, the OLE was installed incorrectly .

Delete the Windows directory and then reinstall WINDOWS.

5 The message appears when opening a VAT.
The "S7USS" directory is missing in the "SIEMENS\STEP7" directory.

Reinstall STEP 7.

6 S7 project is defective and cannot be cleared by "Save as... -> With reorganization".
If it is not possible to copy the STEP 7 project with "Save as..." together with the "With reorganization (slow)", then first check whether there is enough space on the hard disk or drive on which you want to save the STEP 7 project. The reason might also be a missing options package or defective data of an object, for example.

Create a new STEP 7 project and insert an S7-300 or S7-400 station or an S7 program in your project. Copy the blocks from the old STEP 7 project into the newly created STEP 7 project.

7 If you open blocks from the SIMATIC Manager or you open the same blocks via the dialog "LAD/FBD/STL - Program S7 blocks", the following message is displayed:
  • "Cannot find the required DLL file S7AAAPIX.dll".

Check your computer for virus attacks, in particular for the virus type "INTERNET WORM". If the computer has no viruses, then try deactivating the virus scanner and other applications.

8 If you are still using STEP 7 V5.1 and when you open a block, you get an OLE error even though the paths are correctly set in the "autoexec.bat", then you cannot open the HW Config and the metafiles are compiled each time you start the SIMATIC Manager.

An incorrect system date is set.
Correct the system date and restart the SIMATIC Manager.

9 Incorrect or inconsistent installation of STEP 7
Information on this is available in our entry: Tips and tricks for installing and upgrading software in STEP 7" Entry ID: 23568401.
10 A domain user has been added in the Properties of the DCOM configuration.
Start > Run > "dcomcnfg" was called. In the tab: Default Properties > Field: Default Authentication Level a domain user was added via the field: "Edit/change default".

Remove this new domain user and restart the computer. You delete the new domain user in the same field in which you inserted it. Proceed as described above to the "Edit/change default" and mark the user concerned. Delete the access authorization of the user via the "Remove" field. Then reboot your computer to activate the new setting.

11 Another cause for the error message 256:26 could be that in the DCOM configuration, in the "Default Properties" tab, the entry in "Default Impersonation Level:" has been changed from "Identify" to "Anonymous". This conversion might have been done automatically by third-party software. The connection with the internal OLE error has only occurred until now in Microsoft Windows XP.
  1. In Windows you open the dialog "Component Service" via "Start > Run... > Input: dcomcnfg" and open the folder "Component Service".
  2. Right-click the My Computer icon and select "Properties" in the pop-up menu that opens.
  3. In the "Default Properties" tab, change the entry in "Default Impersonation Level:" from "Anonymous" to "Identify".

Fig. 01

Error message, Installation problem

Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit