CauseSuch error means that the packet contains errors or it's version is not compatible with current protocol version that is used by Plesk.
ResolutionXML packet can be validated using 'xmllint' command that belongs to 'libxml2' package, run on Plesk server:
xmllint -schema $PRODUCT_ROOT_D/admin/htdocs/schemas/rpc/PROTOCOL_VERSION/agent_input.xsd FILE.xml
Where $PRODUCT_ROOT_D/admin/htdocs/schemas/rpc/PROTOCOL_VERSION/agent_input.xsd is scheme file for the appropriate protocol version.
Also, for checking XML syntaxis and vier XML packet in comfortable format you can use:
# xmllint --format FILE.xml
Another way, you can enable error reporting on Plesk server where you are sending API request to. Set "display_errors = On" in "$PRODUCT_ROOT_D/admin/conf/php.ini" and restart Plesk CP. After that run API request again. More detailed error should be returned in API response and can be found in "$PRODUCT_ROOT_D//admin/logs/httpsd_error_log" on Plesk server.