There is often the case (as it is with drupal), that your config files will contain files like schema_extra.xml, or solrconfig_extra.xml

In this case, your main schema.xml and solrconfig.xml will contain references to various fields and types that are defined in those extra files.

Therefore, you need to split your config files archive into multiple archives, and upload them as follows:

- First upload the extra files (zip up the schema_extra.xml and other *_extra.xml files and upload that zip first)

- Second upload the main schema.xml file, along with all other resource files, such as stopwords.txt, synonyms.txt, etc.

- Third, upload a zip archive that contains solrconfig.xml alone.