Unexpected Error from the external database Driver (15877)

[moinkhan]

Hi Guys!

I am having a wiered Problem over here..

I have a program which accesses(read only) a Paradox database which is accessed by another program simultaneously(read/write)..

Now.. on my system.. .(where that simultaneously accessing program is not running) the software runs fine.. but on the user's machine where the paradox is accessed by another program as well... it runs fine most of the time.. but periodically it gives the Error
Unexpected Error from the external database Driver (15877)

Although i have made the program to survive this error and starts accessing the database again after closing and re-opening database connection.. Most of the time this trick also works.. but eventually a point comes.. when closing and re-opening no longer works and the program stucks in a looop of Error and resuming and then error... at last the computer hangs.. and everything becomes a mess...

Now My Question is.;
What would be causing this problem? Simultaneous acccess to the database does not seem to be the issue because i have tested it on my system as well...

My Development Machine is running XP Service Pack2

and the user's machine is running Windows 2000 Professional Service Pack 4


That's really urgent...

Any Ideas?

[RobDog888]

moinkhan, In Access you get this same error when you have linked tables to Paradox tables and the length
is greater then 65 characters.
Dont know if that helps much but was just making me think if it had anything to do with querystring length, linked
tables, etc. Or is the version and method of accessing the db are different on the users system from yours.
IE. ADO/ODBC on users and all ADO on yours.

[moinkhan]

moinkhan, In Access you get this same error when you have linked tables to Paradox tables and the length
is greater then 65 characters.
Dont know if that helps much but was just making me think if it had anything to do with querystring length, linked
tables, etc. Or is the version and method of accessing the db are different on the users system from yours.
IE. ADO/ODBC on users and all ADO on yours.

hmmm... Thanx rob for your reply...

What do u mean by length is greater than 65 characters

well.. i am not getting this in Access.. but in VB....

Yah... the version of ODBC Driver is different on my machine and on user's machine...but the operating system is also different..

I have beeen searching for a solution for 12 hours continously.. any idea?

[RobDog888]

Oh, I was referring to the Linked table path of 65 chars max if this was access with linked tables to paradox.

You say that there is another program that also access this database. Do you know how it connects? I have seen
issue araise from connecting to a db using different connection technologies. So if your system is connecting to
the db using odbc and the users system is using only odbc then there should be no problems, but if the users
system is also having anothe program access the db using ado or ex. it could create issues.

Now can you duplicate the other program accessing the db on your system while you are accessing the db
with your program?

[moinkhan]

Oh, I was referring to the Linked table path of 65 chars max if this was access with linked tables to paradox.

You say that there is another program that also access this database. Do you know how it connects? I have seen
issue araise from connecting to a db using different connection technologies. So if your system is connecting to
the db using odbc and the users system is using only odbc then there should be no problems, but if the users
system is also having anothe program access the db using ado or ex. it could create issues.

Now can you duplicate the other program accessing the db on your system while you are accessing the db
with your program?

Hi!!
The program doesn't use odbc to connect to the database,..

Everything was working fine a week ago... i just changed a SQL Query.. and after that... it has become a real mess.. still.. i can get my older exe file to work without error.. really helpless at this point..

I tried trick this thing by linking paradox data to Access and then accessing the data through Access... but this returns the same error message with error number 11270....

[RobDog888]

If the prevoius version was running fine and all you changed was some queries then there has to be something
in the queries that is causing it to error?

Perhaps you could add some auditing code to track the executing of queries and maybe you can pinpoint it down
to a particular query. In the updated querie(s) di you add a new table source?

[moinkhan]

If the prevoius version was running fine and all you changed was some queries then there has to be something
in the queries that is causing it to error?

Perhaps you could add some auditing code to track the executing of queries and maybe you can pinpoint it down
to a particular query. In the updated querie(s) di you add a new table source?

This was the first thing that hit me... I saw all the queries.. see the previous version was

Select A,E0,E1,B,H,J,K from production where A>" & M_GKEY

and i edited it to add two more columns


Select A,E0,E1,B,H,J,K,N,Q from production where A>" & M_GKEY



Well... I also checked the Version of ADO.. in previous version i was using ADO 2.5, and in the newer i am using ADO 2.8.....so now .. i have changed it back to 2.5 again....and till now.. it is working . let's C .. how long
in my point of view; if the version of ADO was the problem.. the program shouldn't have run in first place....
Let me state my problem again..

My program runs fine for number of hours(indefinite) and then starts giving error..... Unexpected error from external database driver.... when i resolved this error(by catching and making my program sleep for 3 seconds and then wake up and retry to connect to the database)....the program ran for longer.. but then it started giving database object not found ......

this is all crazy stuff. .... .

[RobDog888]

I feel your pain. I had a similar experience with 2.7 & 2.7 SP1.
I had compiled a program and packaged it with 2.7 on my desktop. Then during deployment at the client's site
I had to make a change to the exe. I recompiled it on my laptop (2.7 SP1) and when I replaced the exe and
tested it gave unexpected class interface errors.

Didnt realize the same version wasnt backwards compatible.

Good luck on this and I hope it works correctly now

[moinkhan]

I feel your pain. I had a similar experience with 2.7 & 2.7 SP1.
I had compiled a program and packaged it with 2.7 on my desktop. Then during deployment at the client's site
I had to make a change to the exe. I recompiled it on my laptop (2.7 SP1) and when I replaced the exe and
tested it gave unexpected class interface errors.

Didnt realize the same version wasnt backwards compatible.

Good luck on this and I hope it works correctly now

RobDog... This didn't run for so long.. .so I did substantial change in the process i was using to get the data from database.. as the original database table was being used by some other program.. I wrote a procedure which just monitors the original database table file, if it is modified it picks that up and copies it into another folder... then my program started working on it.. and rather than polling up the table for new records indefinitely.. i poll for new records only when the source database is modified... this does work...

thanx for your concern.. and all the prompt support...

[RobDog888]

Cool ,glad you got a workaround, just to be on the safe side you may want to add a delay before the copy is
made to make sure the update process' are complete before you copy the db?

[moinkhan]

Cool ,glad you got a workaround, just to be on the safe side you may want to add a delay before the copy is
made to make sure the update process' are complete before you copy the db?

hmmm.. thanx for the suggestion.. but the modified date is change only when the update to the file is committed.

[Reinosoft]

I had a similar error, it took me a few days to find the solution. (Visual studio 2019)
the SQL connection works fine, but i couldn't open Paradox files with an oledb connection.

it has something to do with security in the manifest file (in the debug/release folder there is a <projectname>.manifest file.

i solved it the following way:

goto the menu "Project" -> "<Projectname> Properties"
click on the left pane "Security" and disable the checkbox "Enable ClickOne security settings"