Troubleshooting¶

Alation Cloud Service Applies to Alation Cloud Service instances of Alation

Customer Managed Applies to customer-managed instances of Alation

For information about logs, refer to Troubleshooting.

Refer to the following scenarios for help in troubleshooting common issues.

Column Extraction Failure¶

Problem¶

In some cases, the Azure Blob OCF connector fails to extract column metadata, even with a successful Test Connection and Metadata Extraction (MDE).

Symptoms¶

Column extraction fails with following error in the Extraction History:
```
accessKey is not a valid Base64 string
```
Test Connection and MDE are successful.

Cause¶

Incorrect Access Key format. The Access Key may contain:

Leading or trailing spaces
Invisible characters such as zero-width space (u200B) or a Unicode whitespace
Introduction of non-printable or non-ASCII characters during copy-paste operation
Line breaks or encoded formatting from password managers, browsers, or word processors

The CData driver does not support the above characters in the key during column extraction. However, the Azure Blob SDK, used for Test Connection and Metadata Extraction (MDE), does allow these characters in a key. This can result in a successful test connection and MDE, even though the key will subsequently cause errors when the CData driver attempts column extraction.

Solution¶

Format the Access Key:
- Paste the key to a plain-text editor of your choice.
- Remove all:
  - Leading or trailing spaces
  - Line breaks
  - Invisible or non-printable characters
Provide the newly formatted key in the Access Key/Shared Access Signature field under the General Settings tab.
Save and click Schema Extraction under Metadata Extraction tab to run column extraction.

Schema Extraction Did Not Start¶

If both Extract Files and Use Schema Path Pattern are disabled, the Azure Blob OCF connector will not initiate schema extraction, even if Test Connection and Metadata Extraction (MDE) are successful.

This is expected behavior. With both options disabled, there are no columns available for extraction at either the file or directory level.

Refer to the table below for details on how schema extraction behaves based on different combinations of the Use Schema Path Pattern and Extract Files settings.

Use Schema Path Pattern	Extract Files	Behavior
Enabled	Enabled / Disabled	Schema is extracted at the directory level for matching patterns. Columns appear only on the directory catalog page.
Disabled	Enabled	Schema is extracted for each individual file. Columns appear on the file catalog page.
Disabled	Disabled	No schema is extracted as there are no columns to extract.

MDE Job Duration Increases After Disabling File Extraction for the first run¶

This is an expected behavior. On the first run after disabling Extract Files, Alation removes previously extracted files, which can result in a longer processing time.