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This issue occurs because due to an a Jira update released by Jira Atlassian that prevents a key Atlassian component from being used by JEMH 3.3.94 and below. In this scenario JEMH will install but cannot be enabled. This was originally fixed for Jira 8.22.3 however, this issue was back ported into Jira 8.13.21 and now requires an upgrade to JEMH 3.3.95 or above.
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