After manually adding custom columns, for example, loading the wspcol table to a server, when selected "save and publish" in Schema Designer, an error "publish_schema failed in backend: Timeout waiting for reply after 60 seconds" comes up as shown below and the schema changes cannot be saved.
<Please see attached file for image>
If we click on the "save and publish" again, the following error appears and the changes will not be saved.
<Please see attached file for image>
The error will appear if a column in the wspcol table referencing to non-existing table name, such as one that does not exist in the out of box schema or the wsptbl table.
e.g.
Non-existing table is specified as a SRel table of a custom SREL column.
A custom column added to non-existing table.
Remove a problematic column from the wspcol table, load it to the Service Desk Manager server, and then select "save and publish" in Schema Designer again after making a dummy change.