Warning! Last repetitions <date> - this message appears if the current system date is much later than the earliest day on which there are repetitions scheduled in a database which is about to be opened. Either your have not been making your repetitions for over 1 month, or your system date is wrongly set. Press Enter if you want to continue or change the system date if it is wrong.

Invalid date! Last repetitions <date> - this message appears if the current system date is earlier than the earliest day on which there are repetitions scheduled in a database which is about to be opened. Either you have mistakenly made your repetitions scheduled for the future, or your system date is incorrect. Change the system date, use your back-up databases or wait until the day for which repetitions are scheduled.

Cannot open <database name> - this message appears if, for any reason, SuperMemo is unable to open a database. Check the following: (1) if all four database files are present in the database directory (note that the DOS's COPY command fails to copy zero-sized files). If not, copy the files from the back-up disk. If you do not have a back-up and only the DAT file is missing, create an empty DAT file and run Tools : Recover or RESCUE.EXE on the incomplete database, (2) if the database files have correct filename extensions (INF, ITI, ITM and DAT). If not, rename them, (3) if there is free space on the database disk. If not, delete some of the files, or use another disk (4) if the door handle of the used disk is closed. If not, close it. If you still cannot open the database, use Tools : Recover or RESCUE.EXE to remedy the problem.

Not enough disk space - this message appears when SuperMemo has problems with writing to the disk. Check the following: (1) if the database path is correctly specified, (2) if there is enough disk space on the database disk (usually SuperMemo will prompt you on how much space is needed for a given operation), (3) if the specified drive is ready for operation

Changes introduced by Mercy/Wipe are irreversible - this warning makes sure that you don't use the Mercy/Wipe option without consideration. You can pass it by pressing Y.

Disk error - this message is presented in most cases when SuperMemo is unable to read or write to a file. You can usually remedy the problem with ease, e.g. by closing the disk drive's door handle, and pressing Enter to repeat the recent disk operation.

Database integrity errors

Upon receiving a database integrity error message, you should immediately stop the learning session, back-up your databases and perform a database recovery by means of Tools : Recover or RESCUE.EXE. Afterwards, compacting the database with Tools : Garbage is recommended.

Each time a database integrity error message appears, you will be asked to press Esc to make sure that you don't miss the message.

Database integrity error messages include:

Database already in use - displayed each time you attempt to open a database which is currently in use with another instance of SuperMemo, or which has not been closed recently, e.g. because of power failure, or which has been closed by termination procedures used to handle fatal errors. In the latter case, you need no more than to choose “No” to open the database; however, you should run Tools : Recover or RESCUE.EXE to check for integrity errors.

Wrong ITM record - displayed if the pointer to the location of the item text points beyond the end of the ITM file

Wrong ITM pointer - displayed if the pointer to the location of the item text points beyond the end of the item record in the ITM file

Wrong assignment pointer - displayed if the repetition schedule contains a pointer to an item which does not exist

Wrong interval - displayed if a memorized item uses a zero interval

Wrong repetition date - displayed if the last repetition date indicates that the repetition took place in the future

Wrong E-factor - displayed if an E-factor reaches beyond the range

Wrong U-factor - displayed if a U-factor reaches beyond the range

Wrong intact pointer - displayed if the intact queue contains a pointer to an item which does not exist

Wrong intact queue - displayed if the first item of the intact queue cannot be located

Wrong optimal factor - displayed if an O-factor reaches beyond the range

Removing unscheduled item - displayed if Delete, Reset, Mercy or Wipe attempt to remove from the repetition schedule an item which is not scheduled

Circular intact queue - displayed if the intact queue is circular