I have installed Moodle 3.1.2. With Oracle 12C.

A) The message that appears in Moodle in the administrator when doing a search in the Glossary is:
Error reading from database
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B) The message that appears in Moodle in the administrator when trying to create a question (matching or multiple choice) is:
Failed to write to the database
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3) The message that appears in Moodle in the administrator when trying to import questions in xml format:
Failed to write to the database
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Once checked this message from DBA Oracle, send us the next explanation, from Database:

Goal Applying to_number to a field containing numbers stored as characters, it returns ora-01722 Example: select to_number('70,59') from dual;

• * ERROR at line 1: ORA-01722: invalid number Solution:
• You need to use format string to indicate the format As follows select to_number('70.59','99.99') from dual;

How can i do resolve this?