Message type: E = Error
Message class:  CNV_INDX - Messages for conversion of INDX-like tables 
Message number: 266
Message text: Failed to select data from table &1 RELID &2
Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.
To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.
Unfortunately, there isn't any extra information in this error notice.
First, use our AnswerBot below to get a possible cause and solution (requires a premium subscription).
Also, review the in-depth Common Questions & Answers listed below; you could discover a solution there or be able to connect with others who have faced similar challenges.
You can also try searching the SAP support portal (support.sap.com) but you need a special user ID to access it. It is possible that an SAP support note exists that provides additional details about the mistake or even steps for fixing it.
The SAP error message CNV_INDX266 indicates that there was a failure in selecting data from a specific table, identified by the table name (&1) and the release ID (&2). This error typically occurs during data migration or conversion processes, particularly when using SAP's data migration tools or during system upgrades. Causes: Table Not Found: The specified table (&1) may not exist in the database or may have been deleted. Authorization Issues: The user executing the operation may not have the necessary permissions to access the specified table. Database Connectivity Issues: There may be issues with the database connection, such as network problems or database server downtime. Data Consistency Issues: The data in the specified table may be inconsistent or corrupted, preventing successful selection. Incorrect Configuration: The configuration settings for the data migration or conversion process may be incorrect, leading to the inability to access the specified table. Solutions: Check Table Existence: Verify that the table specified in the
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_INDX261 Failed to read directory
What causes this issue?  It was impossible to obtain directory from data in table &V1& (RELID &V2&, key &V4&). This usually me...
CNV_INDX260 Failed to read directory in &1 (&2 times); see link
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_INDX300 
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_INDX301 Preparing import / export routines for table &1
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
Click on this link to search all SAP messages.