This file includes only the most dangerous or most frequently misunderstood error messages. If you receive an error that you cannot interpret and that is not listed here (or not explained sufficiently), write to SuperMemoMail

SuperMemo errors are grouped in:

• fatal errors - most dangerous errors that can compromise the integrity of your learning material
• learning process errors - errors that indicate problems with repetition spacing algorithm (Algorithm SM-8)
• local errors - errors that are less severe and may damage single elements in your collection
• warnings - errors that may be ignored

See also: FAQ and Beta-testing SuperMemo 2000

Fatal errors

If you get any of fatal errors listed below, do the following immediately:

1. backup the entire collection with File : Copy collection
2. run the recovery procedure with File : Repair collection
3. if your collection still displays errors after Repair collection, write to SuperMemo World

This is the list of most dangerous fatal errors:

1. Total<Pending - your KNO file has been fatally damaged
2. Total<Memorized - your KNO file has been fatally damaged
3. Writing beyond HugeArray allocation - SuperMemo uses THugeArray type to store various forms of large arrays of information (e.g. item subsets). This error indicates a severe damage to such structures that is extremely dangerous to the integrity of your learning data
4. Reading from beyond HugeArray allocation - SuperMemo uses THugeArray type to store various forms of large arrays of information (e.g. item subsets). This error indicates a severe damage to such structures that is extremely dangerous to the integrity of your learning data
5. Cannot swap HugeArray memory to disk - SuperMemo uses THugeArray type to store various forms of large arrays of information (e.g. item subsets). This error indicates a severe damage to such structures that is extremely dangerous to the integrity of your learning data
6. Cannot reload HugeArray from <filename> - SuperMemo uses THugeArray type to store various forms of large arrays of information (e.g. item subsets). This error indicates a severe damage to such structures that is extremely dangerous to the integrity of your learning data
7. Wrong component buffer marker - file with component information (compon.dat) has been damaged and may result in loss of information from individual elements (most frequently, all components will simply be deleted). You must immediately proceed with verifying the integrity of the collection. Have a closer look at your hardware (esp. reliability of read/write operations of your hard disk)
8. Cannot read data for element

Learning Process Errors

Errors listed below affect the correct execution of your learning process. They do not compromise integrity of your study material; however, they can ultimately lead to a breakdown of the process in which the model of your memory is built and used in scheduling repetitions. If these errors occur, backup your collection and run File : Repair collection with Basic recovery checked

1. UsedInterval<1 in GetRepetitionData - this happens if the learning algorithm finds an element whose last repetitions was made "in the future" (i.e. on a date that is later than today's date). This is most likely a result of using SuperMemo with your date wrongly set in your computer. Important! You should never play with the date to delay repetitions, do repetitions in parts, apply Mercy to a subset of outstanding material, etc. SuperMemo must work with the date set correctly! This is reflective of your learning process and how your memories get consolidated in time.

Local Errors

Errors listed below are less severe and are more likely to be local (i.e. affecting only one or more elements). Once you encounter such errors, it is still recommended that you:

1. backup the entire collection with File : Copy collection
2. run the recovery procedure with File : Repair collection

Local errors:

1. Empty RTF text found at registry member <member number> - this error indicates that a rich text registry member is associated with rich text that is empty. This should not occur in normal circumstances and may indicate a damage to your text registry. Review your text registry, your collection, make a backup and run Repair collection with Rebuild registries checked
2. Cannot compute repetition results - this error should not occur in normal circumstances. It is not dangerous to your data but it may indicate some serious instability of your Windows or SuperMemo itself. Recommended action: restart Windows and run Repair collection (Basic recovery)
3. Parent=nil at MakeVisible changed to Parent=1 - there is a discrepancy between the displayed structure in the contents window and the knowledge structure stored in SuperMemo. The reasons for this error are not known. Try restarting SuperMemo  
4. MMSYSTEM277 A problem occurred in initializing MCI. Try restarting Windows - this is a Windows problem. MCI stands for Media Control Interface and is used by Windows to handle multimedia. MCI functions are called when processing sound and video. However, GIF images processing in SuperMemo may also invoke the function timeGetTime(). If restarting Windows does not help, you may need to reinstall your MCI subsystem. Often, reinstalling your sound board drivers helps resolve MMSystem issues
5. Cannot get the current Contents selection - if this error is followed by Access violation at address ..., the TreeView object in your Windows must have been corrupted (in memory). This is most likely a transient problem and could be remedied by restarting Windows

Warnings

These errors can be ignored or are easily resolved:

• Access denied! System locked by another SuperMemo - SuperMemo will display this message when KNO is locked by another instance of SuperMemo or if the KNO file is set to read-only (e.g. after copying from CDR backup). Remove the read-only status, quit other SuperMemos, at worst, restart Windows
• Element does not belong to the indicated category - this error is likely to occur in the first recovery executed on a collection upgraded from earlier versions of SuperMemo. It is harmless and comes from stricter category registration in SuperMemo 2000
• Error running SuperMemo - most likely this is an error generated by one of Windows modules while executing one of API calls from SuperMemo. This error is not likely to be of much significance. It may, however, indicate some instability of your Windows installation (e.g. incompatible drivers, older DLLs, errors in registry, etc.). This error is by far less likely to occur in Windows NT 4.0 and is mostly reported in old Win95 installations
• Non-zero category number in a template - this error is likely to occur in the first recovery executed on a collection upgraded from earlier versions of SuperMemo. It is harmless and comes from the fact that category information is not permitted in templates in SuperMemo 2000
• Primary storage file: <file 1> occludes secondary storage file <file 2> - secondary storage file is not visible due to an occluding file kept in the primary storage. If you want to restore the visibility of the secondary storage file (e.g. on CD-ROM), delete the file from the primary storage. This can happen if you edit files stored on CD-ROM (the edited copy is stored in primary storage). In SuperMemo 99, this warning would also erroneously be displayed if the collection path was forcibly set do a different case e.g. c:\SM99\systems\ in place of c:\sm99\SYSTEMS\. This could happen by running sm99.exe with a collection path as a parameter string
• Removing a reference to a deleted registry member - this error is likely to occur in the first recovery executed on a collection upgraded from earlier versions of SuperMemo. It is harmless and comes from stricter deleted registry member verification in SuperMemo 2000
• Template registry access error! Prohibited access - Position=<Pos1> - LastPosition=<Pos2> - except for situation in which this error might indicate an error in a template registry, this error is also likely to be reported in collections upgraded from earlier versions of SuperMemo (including collections published in SuperMemo Library). If a category uses a deleted template for tasks or topics, earlier versions of SuperMemo would just ignore it. SuperMemo 2000 reports it as an error and replaces the template reference with 0 (i.e. "no template"). In such circumstances, this error should be reported only once and should have no side effects or harmful consequences
• Wrong A-Factor distribution - the statistics of A-Factor distribution are inconsistent. This error can be ignored in upgrading from SuperMemo 98 or earlier to SuperMemo 99 or later
• Wrong Interval distribution - the statistics of interval distribution are inconsistent
• Error processing escape code

Frequently asked questions

"Fatal error" may indicate a serious file damage in your collection
Some errors in SuperMemo are generated by Windows and can be ignored
In case of persistent errors, use File : Repair collection
"File access denied" error may call for restarting Windows
You cannot open SuperMemo read-only collections
Burden=0 in a collection with memorized items indicates a serious problem
Some errors may be very hard to reproduce and eliminate
Trim Shortcuts turns off Ctrl+Alt+C and some other shortcuts
Up-to-date Mshtml.dll and Shdocvm.dll files are needed to use the HTML component
HTML text exceeds editor capacity

(Tomasz Szkopek, Nov 8, 1999)
Question:
I upgraded Advanced English 97 to SuperMemo 2000 and received the following error: Collection files access error ! Wrong A-Factor distribution. Is it dangerous?
Answer:
No. This is a harmless warning.
After upgrading all collections to SuperMemo 2000, you will always need to run File : Repair collection with Basic recovery checked. This is needed to calculate new values of A-Factors as the interpretation of A-Factors has changed slightly from SuperMemo 98 to SuperMemo 99

Question:
What is the reason of the message "Cannot open collection"?
Answer:
Most likely the collection is already opened by another user or another instance of SuperMemo

(Jiri P., Czech Republic, Saturday, January 13, 2001 8:38 PM)
Question:
In Task Manager : Processes, my Windows NT shows that SuperMemo uses 11MB memory when Advanced English is opened. However, my Actions toolbar shows only 4MB
Answer:
Memory used on the Actions toolbar shows the amount of memory dynamically allocated by SuperMemo. As Advanced English includes 40,000 elements, this allocation is quite high (around 3.5-4 MB). This number does not include the memory used by the program, its static variables, etc.

(Jiri P., Czech Republic, Saturday, January 13, 2001 8:38 PM)
Question:
SuperMemo has just displayed the following error: "Wrong component buffer marker File=C:\Supermemo\systems\Video English Demonstration\info\compon.dat Position=6930 Item #1497: Introducing people L&W"
Answer:
This is a dangerous error that indicates an integrity problem with compon.dat file. Ultimately, this may result in loss of some of your learning material. You should immediately back-up your collection and run a full recovery (File : Repair collection)

(Janusz Murakowski, Sun, Apr 29, 2001 7:55)
Question:
I am using Equation Editor via OLE. I received the following error: EQNEDT32 caused an invalid page fault in module EQNEDT32.EXE at 0167:00426365
Answer:
Errors in OLE components are often entirely independent of SuperMemo. Some application are not stable enough for use with SuperMemo. Others need special workarounds

Error processing escape code
(Jiri Pik, Sunday, July 01, 2001 10:41 AM)
Question:
SuperMemo has just displayed the following error: "Error processing escape code"
Answer:
This is a harmless error that might occur at pressing Esc in the registry window. It is generated by Windows when changing focus between registry controls. It's cause it unknown

"Fatal error" may indicate a serious file damage in your collection
(rocky eversman, Sunday, July 08, 2001 7:35 PM)
Question:
I get the following error message: Fatal error! Cannot read data for element #17498, Choose abort to halt SuperMemo
Answer:
This message indicates that SuperMemo cannot access element information of the 17498th element. You should immediately backup your learning material and run File : Repair collection. At worst, you collection could have suffered a serious file damage to elinfo.dat file, which stores element data. This may require reverting to your latest backup. If file damage results in lost information, SuperMemo may not be able to restore collection integrity

Trim Shortcuts turns off Ctrl+Alt+C and some other shortcuts
(Jiri Pik, Wed, Jun 27, 2001 8:44)
Question:
Why can I not use Ctrl+Alt+C shortcut for selecting the current category in SuperMemo 2000? In the previous releases it worked without any trouble?
Answer:
Make sure you have Trim Shortcuts in Tools : Options : SuperMemo unchecked. This shortcut can be inactivated to compensate for a bug in handling diacritical characters in some national versions of MS Windows

Up-to-date Mshtml.dll and Shdocvm.dll files are needed to use the HTML component
(MZ, Poland, Wednesday, August 08, 2001 5:21 PM)
Question:
SuperMemo 2000 asks for Mshtml.dll and Shdocvm.dll libraries but I got them both in c:\windows\system folder. Is it a bug?
Answer:
You need to make sure that two other conditions are met: 

1. Your Windows is indeed running from c:\windows folder 
2. The files are up-to-date (not older than September 1997) 

Otherwise, SuperMemo will display the following message: "You need Mshtml.dll and Shdocvw.dll installed to use the HTML component". Note that depending on the system, these DLLs can also be located in System32 folder

You cannot open SuperMemo read-only collections
(Chuck Albritton, Mon, Aug 13, 2001 13:51)
Question:
I am using SuperMemo 2000 and tried to open the file below from the MegaMix CD-ROM. SuperMemo has just displayed the following error: "Fatal error! Cannot create registry: F:\English\Languages\Basic Spanish (AudioVisual)\registry\comment. File access denied"
Answer:
You cannot open collections whose files are marked read-only (as opposed to collections opened in SuperMemo's read-only mode). You need to install them on your hard disk first (e.g. with MegaMix Setup or manually by copying)

Some errors in SuperMemo are generated by Windows and can be ignored
(Steve Brown, Wed, Aug 15, 2001 1:03 PM)
Question:
I added a number of cards/elements. Upon exiting, I am getting the following message: " Access violation at address 0055F55B in module 'SM2000.EXE." Read of address FFFFFFFF"
Answer:
This message is most likely generated by Windows and in majority of cases should be harmless. Similar messages with varying addresses (e.g. 004034B4) are most likely in Windows ME or Windows 95/98 due to their instability. As a precaution though, it is recommended that you run File : Repair collection on your learning material at least once if you see this message again. In case it persists, please write to us

In case of persistent errors, use File : Repair collection
(Allen Hall, Fri, Aug 31, 2001 22:37)
Question:
SuperMemo has just displayed the following error: "Fatal error! Cannot open registry files Registry=C:\program files\systems\ALLTOPO SHORTCUTS\registry\category. File not found". I need this collection. Do you know of a fix?
Answer:
In case of collection errors (esp. those listed as fatal), you should do two things: 

1. backup the collection (e.g. with File : Copy collection) 
2. run a checkup procedure with File : Repair collection 

"File access denied" error may call for restarting Windows
(M—, Poland, Mon, Jul 09, 2001 14:00)
Question:
SuperMemo displayed the following error: 
"Cannot reload HugeArray from: 
H:\AAAAAA\SYSTEMS\MICROECONOMICS & MACROECONOMICS\registry\font.ptr 
File access denied"
Answer:
This file must have been mistakenly locked by Windows. This lock could be caused by SuperMemo or by other applications or processes. Restarting Windows should unlock the file. Run File : Repair collection to scan for possible errors resulting from the file lock (SuperMemo might have been unable to update collection data)

Burden=0 in a collection with memorized items indicates a serious problem
(Reto Schmid, Monday, August 27, 2001 1:55 PM)
Question:
SuperMemo has just displayed the following error: "Fatal error! Burden is zero in a collection with 87 memorized elements!"
Answer:
This error is an indication of a major problem in your collection. Burden=0 in a collection with memorized items could be caused by two major reasons: 

1. You manually copied .kno file of one collection onto the same file belonging to another collection 
2. Your computer crashed and the memory image of the .kno file has been overwritten (e.g. with zeros). This image was then saved back to the file rendering your collection unworkable 

You need to immediately execute File : Repair collection. If the problem is limited to .kno file, chances are SuperMemo will be able to recover lost information. However, if Repair collection fails, you may need to restore your most recent backup

Some errors may be very hard to reproduce and eliminate
(Reto Schmid, Monday, September 10, 2001 3:37 PM)
Question:
SuperMemo has just displayed the following error: "ElementNo=0 at CommitElement"
Answer:
Unfortunately, this is a kind of error that upon the analysis of the source code looks like it should never have happened. It occurs when the program requests that the element whose number is zero become memorized (naturally, no such element exists). However, before calling the CommitElement procedure, multiple tests are made to ensure that the element number is valid and existent. This analysis indicates that this error should never have happened assuming stable Windows environment, integral SuperMemo code and its image in memory, and assuming that no bugs at the compiler level (Object Pascal in this case). Without more data and the context, it seems impossible at this moment to confirm the existence of a bug in SuperMemo. This error might be related to: Burden=0 in a collection with memorized items indicates a serious problem

HTML text exceeds editor capacity
(Rodolpho Gurgel de Sousa, Brazil, 24/4/2001 19:24:58)
Question:
SuperMemo has just displayed the following error: "Cannot load HTM text Text exceeds memo capacity"
Answer:
This error appears when you try to edit a very long HTML file in SuperMemo 2000. The problem will not occur in future releases