How to fix 2200T: invalid_xml_processing_instruction in PostgreSQL

First, determine where the invalid processing instruction is coming from. Check if you're using the xmlpi() function or if you're parsing external XML data. Examine the SQL statement or application code that's failing. Look for XML processing instructions (constructs starting with <? and ending with ?>) in your data or function calls.

If you're using the xmlpi() function, verify that the content parameter doesn't contain the ?> character sequence. For example:

-- This will cause an error:
SELECT xmlpi(name php, 'echo "?> hello world";');

-- This is correct:
SELECT xmlpi(name php, 'echo "hello world";');

The content must not contain ?> anywhere, as this would prematurely end the processing instruction.

If the error occurs when parsing XML data, validate the XML for proper processing instruction syntax. Processing instructions must:
1. Begin with <?
2. End with ?>
3. Not contain ?> within the content
4. Have valid XML name characters in the target

Use an XML validator or PostgreSQL's xml_is_well_formed_document() function to check your XML data:

SELECT xml_is_well_formed_document('<?php echo "test"; ?><root/>');

Depending on your needs:
1. Remove unnecessary processing instructions: If they're not needed, strip them from your XML data
2. Fix syntax errors: Ensure all <? ... ?> constructs are properly closed
3. Escape ?> sequences: If you need ?> in the content, you must escape it or use a different approach
4. Use CDATA sections: For content that might contain problematic sequences

For xmlpi() calls, ensure the content doesn't contain ?> and that the target name is valid.

After making corrections, test your XML data or function calls:

-- Test xmlpi() with safe content
SELECT xmlpi(name php, 'echo "hello world";');

-- Test XML parsing
SELECT xmlparse(document '<?xml version="1.0"?><root/>');

-- Test with your actual data
SELECT xml_is_well_formed_document(your_xml_data);

Ensure all processing instructions follow XML syntax rules before attempting to parse or store the data.