As has been noted in https://big.ideas.aha.io/ideas/APP-I-1873, if you have an Aha / Jira integration setup to connect Aha tags to Jira labels, the push from Aha to Jira fails if there are spaces present in the tag value. The admin response in that ticket states "If you want to integrate Aha! with JIRA then within Aha! you must use tags that meet JIRA's limitation of no spaces in tag names." While I agree that is the solution to the problem, there is currently no way to enforce that users do not use spaces in their tags.
That idea suggested automatically swapping underscores for spaces in tags, which I agree is not a good solution. However, it really would be nice to be able to enforce the "don't use spaces in tags" rule for those of us with Jira integrations connecting Aha tags to Jira labels (I suspect there are many of us).
I propose an overall account level setting that can be toggled on/off to disallow spaces in tags, When enabled, anyone entering a tag with a space in it would get an error and not be allowed to continue. For Aha instances without a Jira integration (or where they are not integrating Aha tags with Jira labels), they could leave this setting toggled off, thereby allowing spaces in tag entry.