The control file CARDBOX.SHR is crucial to the correct operation of networking versions of Cardbox.

• There must be only one CARDBOX.SHR file on the network.
• Every user must have full read/write access to it.

If these conditions are not met, then you will see error messages and you may get database corruption.

Why CARDBOX.SHR is important

In order to administer multi-user access correctly, Cardbox needs to identify each active user with a unique number, and it uses CARDBOX.SHR to do this.  CARDBOX.SHR has a list of the names of current users of Cardbox (you can use the Cardbox network utility to view this), and a user's user number is simply the position of his name within the list.

If you have more than one CARDBOX.SHR file, then one user can be "user 1" in one file while another user is "user 1" in the other.  Cardbox tries to detect this condition, but if undetected it can give rise to serious data corruption.

Problems when starting Cardbox

Cardbox cannot locate the share control file CARDBOX.SHR. Without this file, Cardbox cannot run.  Browse? Create?

Cardbox cannot find CARDBOX.SHR.

• If CARDBOX.SHR genuinely does not exist, perhaps because you have just deleted it by hand, then press Create.
• If CARDBOX.SHR does exist on your network, then press Browse and tell Cardbox where to find it.  Do not press Create.
• If CARDBOX.SHR exists on your network but is temporarily inaccessible (for example, you have started your workstation before the server has started), do not press Create.  Just press Cancel and try again later, when the network is fully operational.

CARDBOX.SHR does not contain your computer's machine name. Cardbox cannot start.

This happens when a user does not have read-write access to CARDBOX.SHR.  Use your networking system's administrative commands to give the user full read/write access.

Error: duplicate machine name. A machine called name is already registered in the control file. Cardbox cannot start.

Some networking systems do not use the standard DOS conventions for assigning machine names, and as a result it is possible for two different computers on a network to be given the same name.  In this case, you will have to change the name of one of the computers.  The "Networking" section of the Cardbox on-line help gives full details of how to deal with machine name problems.

It is also possible for this error message to appear if your computer (or Cardbox) crashed the last time you used it, so that Cardbox never had a chance to remove your machine name from CARDBOX.SHR.  If you are sure that this is what happened, you can press the F1 key and read the on-line help to see how to override the error.

All these error messages actually quote the full path name - for example, V:\SHARED\CARDBOX.SHR.  Make an exact note of the name that they report, character by character, before you close the message box, because you may need it when using network commands to resolve the problem.

Problems when opening a database

Your network has more than one CARDBOX.SHR file, and this has caused a user number conflict. There should only be one CARDBOX.SHR file per network.

This message will not necessarily appear on everyone's workstation.  It will appear only when two users of a particular database have the same user number from two different CARDBOX.SHR files.  Since the event that caused two different share files to exist may be some time in the past, the cause can be difficult to diagnose.

The simple method of resolving this problem is as follows:

1. On every workstation that is running Cardbox at that time, enter the command Help, About and then press the button marked More.  Near the beginning of the report that appears on the screen, you will see a line that starts CARDBOX.SHR=.  This gives the name of the CARDBOX.SHR file that this workstation is using.
2. Work out which CARDBOX.SHR file is the genuine one, and which one(s) should not exist.
3. Get everyone out of Cardbox, and delete all CARDBOX.SHR files except the genuine one.
4. Let people back into Cardbox.
5. Whenever anyone sees the message "Cardbox cannot locate the share control file...", do not let them press Create.  They should press Browse and direct their copy of Cardbox to look at the genuine CARDBOX.SHR.

If this simple method does not appear to resolve the problem, then perform a radical clearout, as described below.

If you are asking a group of users to perform the Help, About, More check, you may prefer to get them to save the report to a file or print it out, rather than rely on them to copy the right filename and copy it exactly.

It is important to get everyone completely out of Cardbox before making any deletions, because networking systems behave in odd ways if you try to delete or rename a file while it is open.  Some of them even appear to have made the deletion even though they haven't, which causes endless confusion.

Performing a radical clearout

If the simple solution doesn't appear to work, or if you want an absolute guarantee that you will not get conflicts in the future, then a more radical approach is needed.  There are four steps: search, destroy, check, and rebuild.  You will need the cooperation of all your users.

1. Search

• Find all the copies of CARDBOX.SHR that you can.  You can do this using your operating system's own file search facilities, or by using Help, About, More as described earlier in this document.  Make a list of them all.

2. Destroy

• Get everyone out of Cardbox. 
• Delete or rename every single CARDBOX.SHR that you have found, even the one that you think is the right one.

3. Check

• Make everyone try to get back in to Cardbox.  Everyone should fail (they should see the message "Cardbox cannot locate the share control file...").
• If anyone doesn't fail, then they must be using a CARDBOX.SHR that you missed.  Identify it (use their Help, About, More) and destroy it.
• Do not allow anyone to press the Create button when they see the error message!

4. Rebuild

• Decide where you want the real, unique, genuine CARDBOX.SHR to be.
• Run one copy of Cardbox.  It will report that it can't locate the share file.  Press the button marked Create, and make Cardbox create CARDBOX.SHR in the location you have chosen.
• Use your system's facilities (Explorer, etc) to make sure that CARDBOX.SHR has indeed been created in the right place.
• Now get everyone else to run Cardbox.  If any of them gets "Cardbox cannot locate the share control file...", they must press Browse (not Create) and navigate to the CARDBOX.SHR that you have created for them.

When we say "Delete or rename", this is simply because renaming doesn't destroy anything, so if you rename instead of deleting, you have the reassurance that if you get into a mess then you can put things back to the way they were.  Choose an obvious name like DELETEME.TMP as the new name.