when more than certain amount of data is present in a SAP R/3 table, data migrator is not able extract the data,

after some point of time (15 - 45 mins),we are getting this error,

SAP/R3 REQUEST ERROR: RFC_ERROR_PROGRAM
SAP/R3 ERROR EXECUTING ABAP4 PROGRAM : <objectName>

- The SAP synonym doesn't contain any RAW data types
- Adapter is a SAP R/3 4.6C - ECC 5.0, 6.x Non Unicode
- DM Version: 7.6.11

SQL is some thing similar to this,

SELECT
T1.BSIS_MANDT , --Client
T1.BSIS_BUKRS , --Company Code
T1.BSIS_BELNR , --Accounting document number
T1.BSIS_GJAHR , --Fiscal year
T1.BSIS_BUZEI , --Number of Line Item Within Accounting Document
T1.BSIS_HKONT --General ledger account
FROM
v04_bsis T1
WHERE
T1.BSIS_MANDT = '026' AND
T1.BSIS_BUKRS NOT IN ( '3218' , '3284' ) AND
T1.BSIS_HKONT IN ( '2240000000' , '2210300000' )

RFC trace is as shown below:

15.06.55 CC -SAPPAS : Function Name : ZIBI
15.06.55 CD -SAPPAS : Calling Rfc Function - RfcCallReceive
15.09.22 CD -SAPPAS : Returning from Rfc Function - RfcCallReceive
15.09.22 CD -SAPPAS : RC = 3
15.09.22 CB -SAPPAS : exited. Errcode= -1; ibiSapExFunction
15.09.22 CB -SAPPAS : entered. ibiSapLastError
15.09.22 CD -SAPPAS : Calling Rfc Function - RfcLastErrorEx

What are the possbile reasons for getting this kind of error, and what is/are the solution(s)?

Appreciate your help.

The product manager for SAP suggests that you look at the dev_rfc and rfc traces for cause of the error. If it's not apparent then please open a hottrack case and post the traces and he'll take a look at them and suggest further.