As noted in this Q&A the workaround is to browse to configure on the matrix configuration and uncheck Disabled.
Clearly one bug is that a matrix configuration got disabled somehow, i.e. the MatrixConfiguration.disabled field was set. How?
The next bug is that configure (and configSubmit) are even available on matrix configurations (albeit without a sidebar link), when there does not seem to be any intent for these config.xml files to be individually configurable. (The configure page shows all sorts of options, such as SCMs, which are definitely not supposed to be allowed on configurations.) These URLs should presumably be blocked. The config.xml URL is also available; in GET mode this might be OK, but a POST to it is probably also bad.
Then there is the problem that despite the fact that MatrixConfiguration.supportsMakeDisabled is false, so no UI button appears to explicitly enable or disable the project, isDisabled is not overridden to unconditionally return true.
As noted in this Q&A the workaround is to browse to configure on the matrix configuration and uncheck Disabled.
Clearly one bug is that a matrix configuration got disabled somehow, i.e. the MatrixConfiguration.disabled field was set. How?
The next bug is that configure (and configSubmit) are even available on matrix configurations (albeit without a sidebar link), when there does not seem to be any intent for these config.xml files to be individually configurable. (The configure page shows all sorts of options, such as SCMs, which are definitely not supposed to be allowed on configurations.) These URLs should presumably be blocked. The config.xml URL is also available; in GET mode this might be OK, but a POST to it is probably also bad.
Then there is the problem that despite the fact that MatrixConfiguration.supportsMakeDisabled is false, so no UI button appears to explicitly enable or disable the project, isDisabled is not overridden to unconditionally return true.