FAQ: Files and backups in SuperMemo

See also:

Use Copy collection to easily copy your learning material to any location
(cmartin336, Thu, 27 Sep 2001 07:06:02 EDT)
I had bad experience with the copy feature of SuperMemo. It looks like one cannot determine, where one wants to store the copied file
File : Copy collection
makes it possible to select the destination. Probably you are using Quick backup which quickly saves a backup at a predetermined location. However, this location can also be changed

You should regularly make a full safety copy of your collection
(Adam, Australia, Tue, May 22, 2001 6:49)

I want to optimize my backup strategy. When I do repetitions only, and do not modify anything, I could probably use export/import learning process only. How could I export/import a subset of the collection, like newly added knowledge elements, including sound/html files (assuming I only use the same set of templates)?
It is always safest to make a full copy of the collection. You should use File : Copy collection on a regular basis (e.g. every 1-2 weeks depending on the intensity of your work). If you do not change the content (e.g. by editing questions, etc.), File : Export : Learning process will suffice to back up the learning process. Note that Export : Learning process  process cannot be executed on a subset of elements. If you want to backup only a newly created branch, you could just transfer this branch to a new collection but you must be cautions as some global settings are not subject to transfer. In addition, restoring such a backup is not trivial. You will need to transfer the branch back to an earlier backup of the entire collection. In other words, File : Copy collection is the simplest and safest way of backup

Storing SuperMemo in a safe place
(Ewa K., United Kingdom, Aug 08, 2004, 22:41:24)
Can you tell me for computer-idiots how to store my SuperMemo so that it won't get lost?
Install SuperMemo in a distinct folder that you can easily find. For example: c:\SuperMemo. Keep SuperMemo and all your collection in this folder. From time to time, you can backup this entire folder on a CDR or any backup device. When you later restore the folder, both SuperMemo and your learning material will be restored. You can also restore the same folder on another computer. Read about backup devices in your computer manuals. Read about backup strategies for SuperMemo. These differ and there is no single algorithm that would be universal for all cases. Remember, that you do not need to worry about losing SuperMemo. You can always get it back from us. Be sure only that you take care of your learning material. This is irreplaceable.

If SuperMemo loses its vital files, you may need to restore the whole collection from a backup
(Juarez Barreto, Brazil, Friday, August 30, 2002 3:35 AM)
SuperMemo displayed the following error: 
  "Collection files missing! 
  Try to restore files that you have moved or deleted"
On opening a collection, SuperMemo checks if its vital files are in place. If any of these is missing, the above error will show. Vital files are those that make recovering the collection impossible. For example, the text.reg file contains the texts of your elements. If this file is missing, SuperMemo will not be able to recreate the texts used in your collection. This will render it useless. Most likely reasons for the above error: 

  1. you moved the kno file without moving the associated folder. For example, if your collection is Meus then it is made of the file Meus.kno and folder [Meus]. If you move Meus.kno to the root of your c: drive and then try to open Meus.kno, SuperMemo will protest the absence of the [Meus] folder by displaying the message above
  2. you deleted, moved or renamed the folder associated with your collection (e.g. c:\meus associated with c:\meus.kno
  3. due to a virus, software or hardware malfunction, one the the vital files was deleted or its size was set to zero If you are unable to restore the deleted folder or files, you will need to resort to your most recent backup of the collection

Important: If you are not fluent with files and folders, it is safer to copy or move SuperMemo collections with tools available on the File menu (for example, File : Copy collection). Otherwise, it is very easy to pick the kno file in Windows Explorer and separate it from the rest of the collection. The error message as above will result

Use Copy collection on the File menu to avoid backup errors
Przemek S, Poland, June 8, 2000)

I used to regularly back up my Advanced English on a second hard disk. Today I tried to restore my backup and ... it looks as it is empty! Only one element inside! Help!!!


There is a frequent mistake users make. To backup a collection, you need to copy both the kno file and the associated folder (e.g. file ae.kno and the folder [ae])(see: Collection files). Some inexperienced users copy only the kno file which is just 20KB of data! If you try to open an orphaned kno file, SuperMemo will reconstruct an empty folder structure.

To avoid this problem: Always back up collections with File : Copy collection or File : Tools : Quick backup. Do not use external tools unless you understand Windows, files, folders and SuperMemo very well!

To resolve the problem: it is possible the original folder associated with the kno file still exists on the hard disk! You can search for some files characteristic for SuperMemo (e.g. burden.dat or sm8opt.dat). Make an inventory of all kno files (search for *.kno) and all SuperMemo collection folders (search for burden.dat) on your hard disk. Once the inventory is made, try to carefully match up knos and folders and copy kno files to match the folders. Chances are that File : Open collection on one of these files will restore the lost backup. Note that you can easily find empty collections by checking the size of burden.dat. This file contains repetitions and is zero-sized on collections with no learning process

My learning material keeps disappearing
(hojinil, South Korea, Wednesday, April 11, 2001 4:29 AM)
I used Add New and I added lots of stuff but next time when I opened collections I couldn't find any of them. It was gone!
Please make sure the following two conditions are met: 

  1. You are not copying or moving files behind the back of SuperMemo (e.g. with Windows Explorer) 
  2. With File : Open collection, you go to the exactly same location where you last left your collection 

If some files are moved or deleted behind the back of SuperMemo, it will often attempt to recreate missing files and open the collection regardless. Unless you delete your collection or delete its folders, your learning material should remain safe.

If you happen to own more than two versions of SuperMemo, or installed SuperMemo more than twice, check which SuperMemo is running. Each installation will keep its own list of default collections. Your two collections might have the same name but be kept at two different locations. The collection location is displayed on top of the docking toolbar

To start from scratch, move SuperMemo to a new folder (#13070)
(Jason & Christa, Thursday, March 01, 2007 1:54 AM)
I would like to get a refund. I will erase absolutely everything on my computer, and then I will repurchase the product. The entries my wife have entered are nowhere to be found and I am unable to get my friend's collection into SuperMemo for Windows. Your FAQ question page was not helpful and I am sick and tired of spending time trying to figure this out. I am willing to give it one more chance, but only if we can start over from the beginning
You do not need a refund to repurchase, you do not need to repurchase to reinstall, and you do not need to reinstall to start over from the beginning. For information about refunds, respond to your original order notification e-mail. To reinstall, run SuperMemo installer again and choose a new installation location (new folder). To start from scratch, do the following: 

  1. move SuperMemo to a new empty folder in Windows (e.g. move the file SM15.exe if you have SuperMemo 15) 
  2. start SuperMemo in the new folder (e.g. double click on the moved file: SM15.exe) 

Note that SuperMemo does not need an installation process to run from any location. Once you make a clean start, all you need to begin work is two keystrokes. If you cannot locate your original collections or have problems with transferring collections, read about files and backups (also: FAQ). If FAQs are not helpful, you need to describe your situation in more detail. Current description is general enough to have many possible interpretations. A simple explanation might be that you deleted your collection files or portions of your knowledge tree. You might have moved your collection or its portions on the hard disk. You may have problems with using somebody else's collection if the collection you received is incomplete. In other words, to narrow down the reasons for your troubles, you need to describe your steps in details. If SuperMemo terminology is difficult, you can illustrate your steps with screenshots.

You can easily copy SuperMemo to any backup medium
(Jack B., Sun, Jun 24, 2001 2:20)
After getting the program downloaded, may I simply pay for a backup medium (e.g. CD-ROM) sent to me?
No. We do not send out backup CD-ROMs. You can easily create a backup yourself in a few minutes. However, if you fail to backup or your backup is lost, you can always write back to receive a replacement via download

Files missing or zero-sized (#13457)
(M.  Ponti, Canada, Friday, October 18, 2002 5:50 AM)
SuperMemo has just displayed the following error: 
"Collection files missing! 
Folder=D:\Program Files\Supermemo\systems\Spanish 100\"
All I wanted to do is copy my collection and when I clicked on copy, it gave me the error. I haven't been able to recover it as the .kno file has zero bytes now, and the supporting directory structure is gone
You need to begin with mastering the backup skills. Most importantly, you should use SuperMemo to copy your collection (File : Copy collection), not other tools (unless you are sure which files are part of SuperMemo collection). You should not experiment with incremental backups as these usually lead to lost integrity of the learning material. 

You can possibly still recover lost work if you reassemble your collection. Your <collection>.kno file must have been separated from <collection> folder. If you search your hard disk for lost components, you can still put them together (unless these have been deleted or damaged). You will find detailed file structure and some FAQs for similar emergencies here

Occasionally, the above error could also result from a software or hardware crash (e.g. one of vital collection files has been deleted, destroyed or made zero-sized). In such circumstances, you may need to resort to your most recent backup. Zero-sized KNO file may indicate a crash. SuperMemo never creates zero-sized KNOs. These could only be created in abnormal circumstances such as a major software crash

To restore a CDR backup, you need to remove the read-only attribute
(trojanma, USA Educational, Tuesday, October 22, 2002 7:16 PM)
My hard drive recently crashed, but I had a copy of SuperMemo on CDR. When attempting to run SuperMemo after copying it back to my computer there was an error that said the database was read only. I am a medical student and I have created a database of hundreds of questions. It will be disastrous if I lose them. What can I do?
It should be enough if you remove the read-only attribute from the files you copied from the CDR. While copying files to the CDR, all files are automatically marked as read-only. SuperMemo cannot use read-only files as it needs to write your learning data back to the collection. For example, in Windows Explorer, you can right click over files or folders, choose Properties and uncheck General : Read-only

Wrong size of KNO data
(Dirk Ceulemans, Belgium, 26/01/2003 13:18:28)
SuperMemo has just displayed the following error: 
"Wrong size of the DataRecord in the *.kno file 

SuperMemo stores vital collection statistics in the file named <collection name>.kno. Before you begin working with the collection SuperMemo checks if the size of the KNO file is correct. The displayed error indicates that either SuperMemo cannot read data from the KNO file or that its size is zero. Problems with reading may occur when the file is locked (restarting SuperMemo or Windows will usually remedy the problem). However, if the size of the KNO file is zero, you will not be able to use the collection. The file might have been lost due to a computer crash, virus or problems with your hard disk. In such cases, you will need to resort to your most recent backup file.
In older SuperMemos the same message reads:
"Wrong size of kno.DataRecord 

Restoring SuperMemo backup is easy
(andon, South Africa, Thursday, February 13, 2003 8:30 PM)
How do you restore a backup?
You only need to copy the backed up files into the folder where you want to use them. See: Backing up
Remember to remove read-only protection if you copy from a CDR. 
Remember to restore both *.kno file and its associated folder (using File : Copy collection is safest)

Collection is blank
(Simon, Thursday, April 17, 2003 2:10 AM)
I received the following messages: 
"Image registry access error cannot determine format for position 28794", 
"Image registry access error cannot access registry", 
"Cannot verify member status at position 28794
The whole knowledge collection is now blank
There must have been a major mishap with your collection files. It is possible your material is unrecoverable, and you will need to resort to your most recent backup. Most likely causes of similar events are: 

  1. deleting important folders in the collection 
  2. copying one collection over another 
  3. major hardware or software problems (e.g. hard disk errors, viruses, etc.) 

To make sure #1 or #2 do not happen in the future, read Backup and Recovery

Problems after System Restore
(Marcos Rufino , Non-Profit Organisation, Wednesday, May 28, 2003 1:34 PM)
I've noticed a problem using SuperMemo with System Restore in Windows XP. After using the System Restore to fix some problems with my Windows, one of my SuperMemo collections became scrambled. All the registries appeared filled with some outlandish characters
This problem is not likely to be directly linked to System Restore, which should only affect system files. Indirectly, System Restore could have affected a corrupt file system. How this could have modified files used by SuperMemo is very difficult to figure out. Probably Microsoft would have a better answer to this question. Independently, this will be posted as FAQ to leave a documented trace of the case. We advice a regular (e.g. weekly) backup of all collections as well as an additional backup while doing any major changes to the system software or hardware

If you restart your computer, SuperMemo will open the last but one collection in use
(Zoran Maksimovic , Monday, August 04, 2003 3:20 PM)
When I reset my PC when SuperMemo is running, my usual collection is not loaded. Instead, SuperMemo loads a backup copy. Could this result in corrupted data?
Resetting your computer during file write operations is always dangerous and can result in loss of data. However, SuperMemo collections are kept up-to-date most of the time (i.e. SuperMemo does not keep vital data in memory for long). As a result, damage is rare and nearly always recoverable with File : Repair collection. However, SuperMemo writes down the name of the last used collection only at the moment of closing this collection. Consequently, it will reopen with the last collection used before the one that was subjected to the computer restart. This behavior is important in case of problems with the collection itself. In case of a serious error, SuperMemo will give you a chance to back up your material before it attempts to reconstruct any missing data

Damaged KNO file may require restoring a backup
(Caroline Item , Belgium, Mon, 4 Aug 2003 09:04:26 +0100)
SuperMemo displayed this error: 
  KNO file is damaged! 
  c:\program files\SuperMemo\systems\ENGLISH BBC.Kno
The KNO file is the file where SuperMemo keeps its vital statistics. The Total field indicates the number of elements in the collection. Total=0 indicates damage to the KNO file (the smallest collection must contain at least 1 element: the root element). If File : Repair collection does not help, you may need to resort to your most recent backup. The most likely reason for damage to the KNO file are major software crashes or physical damage to files on the hard disk due to software or hardware malfunction

"Cannot open template.lst" may be a result of a file lock
(j.b., USA Educational, Sunday, September 28, 2003 1:54 AM)
I received this error and don't know what it means: 
Cannot open C:\Documents and Settings\jason brody\My Documents\smemo030907\03 09 24\KOREAN151\registry\template.lst
Most likely, the listed file has been locked. An exemplary reason could be a software crash (with or without SuperMemo). In case of a file lock, restarting SuperMemo may help in some cases, but restarting Windows may also be necessary. After rebooting, you will need to run a full File : Repair collection to try to fix possible integrity errors resulting from the file lock.

Learning with a back-up by error
(Reinhard, Germany, Tue, 25 Sep 2001 23:20:34 +0200)
I just had a traumatic experience. I spent the whole day in vain learning only to discover now that I spent the whole time with the wrong collection. I learned with the backup instead of the original.
One of the following must have happened. Either you can easily recover from your error or there has been a major departure from the art of learning with SuperMemo:

  1. If you started learning with a backup soon after creating it, all you need to recover is to copy your backup over the original, and create a new backup
  2. If you kept learning with an old backup, you should have recognized the repeated material (assuming you stick to the rules of SuperMemo Decalog). On one hand, this should make you think why freshly repeated material has not been identified (this is a norm in SuperMemo). On the other, the damage resulting from repeated exposure will be little (you do not seem to recognize the material anyway). Naturally, it might have happened you added some new material to the original before making repetitions with the backup. In such a case, simply transfer the new material to the backup by means of a subset transfer. Another special case is where you do not recognize the material due to heavy overload in incremental reading. In such a case, you can simply transfer new material to the backup and keep learning as if nothing happened. The heavier the overload, the lesser the chance of repeated exposure, and the lesser the damage

Should backups be kept inactive?
(Reinhard, Germany, Tue, 25 Sep 2001 23:20:34 +0200)
A backup should not be accessible as any other collection. I just started learning with a backup instead of an original. A backup is supposed to be totally passive until actively activated.
In most other applications, the backup differs from the original only in name. For example, if you save a file in MS Word as "Homework Backup", it is your responsibility to ensure you do not start working with the copy instead of the original. If you used File : Tools : Quick backup to make a backup, SuperMemo will recognize it is a backup collection, and will ask you if you are sure it is the collection you want to work with. Additionally, SuperMemo will easily help you recognize your error. After a few repetitions you will notice "I have already gone through this material recently". It is true that some users start learning with their recent backup, but they easily recover by copying the backup over the original. However, there have not, until now, been reports of users duplicating their work by error in backup

Use File : Delete collection to delete collections
(Daniel McCarthy, Apr 20, 2004, 20:28:03)
When I do a Quick Back-up, I get a new icon and a new folder in my SuperMemo\Systems\Backup Folder. If I try to delete the previous icons or folders, then open SuperMemo, I get a warning that files have been lost, and they should be repaired
You would best delete collections with File : Delete collection in SuperMemo. Otherwise you can easily mismatch deleted folders and files and produce incomplete collections that report said errors

Problems with finding a collection to open
(John B., Non-Profit Organisation, May 01, 2004, 01:35:40)
I tried going to File : Open collection and there was a dialog box for elements, registry, etc., but nothing opened up
Folders such as elements, registry, info, etc. are part of your learning material. However, to access this material, you need to go a folder up and look for files with the extension KNO. Only these are openable

Question-answer format is universal to all versions of SuperMemo
(Mark Yang, Saturday, August 25, 2001 12:33 AM)
How can I import a text-based file in to one collection? For instance, if I've already created a tab-delimited file (compatible with SuperMemo Palm version), how can it be imported?
You need to convert your file to question-and-answer format acceptable by all versions. See: File menu for more

Use template tags to export collections with an HTML template
(Piotr M., Poland, Sep 23, 2000)
I use HTML export template but only one page gets exported and it does not include any collection material
You need to use template tags such as #Pages#, #Element#, #Content#, #SuperMemo#, #Author#, #Download# to insert collection components. Insert all those tags in different places and see what happens

Saving SuperMemo for later use
(Bob Walter, Jun 18, 2004, 20:28:41)
Along with SuperMemo for Windows I ordered the Palm Pilot version. I do not yet own a Palm Pilot. Can I save this application in my PC using windows?
Yes. You can simply store the downloaded file on your hard disk. Download later from our website, or simply ask for assistance in the future once you own Palm Pilot. Your order will remain in our records and is easily identifiable

You can copy your SuperMemo folder to move the program to a new location
(William Rocker, Tuesday, July 20, 2004 4:08 PM)
Can I transfer SuperMemo and my data files to my laptop?
Yes. You can simply copy the entire SuperMemo folder onto the laptop. That will transfer all your settings, collections, the program, etc. You may only need some fine-tuning in Windows (e.g. installing fonts, if any, setting up shortcuts, etc.). Remember that collections stored in folders outside the SuperMemo folder will not transfer and will need to be copied separately. SuperMemo does not need to be reinstalled in the new location in any way. More about files, their locations and functions: Files used in SuperMemo

File browser lists files in the middle panel (#27043)
(Patrick, Aug 04, 2004, 14:04:19)
I had expected that when went to File : Merge collection and then double clicked on the appropriate collection in the leftmost panel that this would allow me to merge the old collection with the new collection. All that happens when I double click any of the commercial collections in the left panel is that it simply opens up ELEMENTS, INFO, REGISTRY folders etc: whilst blanking out both the center and right panel
The file browser includes three panels: 

  • the left panel lists folders 
  • the center panel lists files 
  • the right panel is used for a preview 

When choosing collections or other files, always use the middle panel and choose the appropriate *.KNO file. Use the left panel only if you want to search for files in other folders

Preserving old collections during an upgrade (#28965)
I'm using SuperMemo 2008 and I have two own collections. They are notes from my English lessons. Since I want to uninstall SuperMemo (because I was inexpert and I did a lot of mess) and buy SuperMemo 15, I would like to know how to store these two collections in a folder and re-use them after having installed SuperMemo 15
It is enough you use File : Copy collection to copy your two collections to a clean/empty folder (e.g. c:\MyCollections). After installing SuperMemo 15, use File : Open collection and open your collections in their new location. Please read this text carefully: Backup