The invalid_xml_comment error (SQLSTATE 2200S) occurs when PostgreSQL encounters an XML comment that violates the XML 1.0 specification.
invalid_xml_comment is a PostgreSQL XML processing error appearing as “ERROR: invalid XML comment” when a comment inside an XML value breaks XML 1.0 rules (for example, contains “--” or is not properly closed). Remove or escape the offending comment, or build the XML with PostgreSQL’s XML constructors to resolve the issue.
invalid_xml_comment
The PostgreSQL error “ERROR: invalid XML comment” signals that the database parser found an XML comment that violates XML 1.0 rules while casting text to XML, using the xmlparse function, or querying XML columns.
The server aborts the statement with SQLSTATE 2200S to prevent storing or returning malformed XML that could break downstream processors or violate standards compliance.
XML comments must start with “”.
Any deviation - extra dashes, missing terminators, or nested comments - triggers the error.
The error also appears when an application concatenates user input into an XML string without sanitizing special sequences, or when a migration script inserts legacy XML that predates current standards.
Locate the malformed comment by searching for “--” inside XML values or by isolating the row that fails CAST or INSERT.
Replace illegal sequences with “- -”, escape them, or remove the comment entirely.
When generating XML in SQL, prefer PostgreSQL functions such as xmlcomment(), xmlelement(), or array_to_xml() to ensure comments are encoded safely.
Bulk import scripts often fail because CSV data holds raw XML with bad comments.
Run a preprocessing step that strips or fixes comments before COPY.
Dynamic query builders that splice XML fragments at runtime should switch to parameterized functions to avoid accidental “--” sequences.
Validate XML with XMLPARSE or the pgxml extension before storage. Reject rows that fail.
Use application libraries that escape or disallow comments in user-supplied content. Add tests for XML compliance in CI pipelines.
invalid_xml_processing_instruction occurs on malformed PI sections.
invalid_xml_content errors surface on unexpected characters outside tags. Fix them by sanitizing content and relying on XML constructors.
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Wrap the insert or update in a SAVEPOINT and binary search the XML text with substrings until the minimal failing snippet is found.
No. PostgreSQL follows XML 1.0. Comments that exploit 1.1 relaxations will still fail.
Validation is mandatory when casting to the xml type. Store the data as text if validation is undesirable, but downstream code must then handle parsing.
Galaxy’s inline XML linter highlights invalid comments while you type, and its AI copilot suggests xmlcomment() or xmlelement() functions, preventing malformed strings from reaching production.
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