An adapter assembly for connecting a surgical stapler to an electromechanical handle assembly, the adapter assembly comprising: an outer tube; a trocar assembly releasably securable within a distal end of the outer tube, the trocar assembly including a tubular trocar housing defining a pair of openings or recesses in the outer surface therein, wherein the pair of openings or recesses are in opposed radially extending relation to one another; and a trocar assembly release mechanism configured to releasably secure the trocar assembly within the outer tube, the release mechanism including: a pair of release buttons rotatably supported on opposed radial sides of the outer tube, wherein each release button is selectively receivable within a respective opening of the pair of openings or recesses formed in the trocar housing, each release button being movable between a release condition and an engaged condition; and a pair of biasing members supported in the outer tube and associated with a respective one of the pair of release buttons, wherein the biasing members urge the pair of release buttons to the engaged condition and into engagement with the trocar housing; wherein, when the release buttons are in the engaged, locked condition, the release buttons are disposed within the pair of openings or recesses of the trocar housing to maintain the trocar assembly connected to the outer tube; and wherein, when the release buttons are in the release depressed, unlocked condition, the release buttons are disengaged from the pair of openings or recesses of the trocar housing to release the trocar assembly from the outer tube; each release button defines a proximal face projecting to a tail (1275a"), wherein when the trocar assembly is properly inserted into the outer tube, the release buttons are urged radially inward, to the locked condition, by the biasing members rotating the release buttons such that the tails thereof are received in the openings or recesses in the trocar housing to provide a visual indication to an end user that the trocar assembly is properly inserted into the outer tube and wherein when the trocar assembly is not properly inserted into the outer tube, the release buttons are urged radially outward, to the unlocked condition, to provide a visual indication to an end user that the trocar assembly is not properly inserted into the outer tube. an outer tube; a trocar assembly releasably securable within a distal end of the outer tube, the trocar assembly including a tubular trocar housing defining a pair of openings or recesses in the outer surface therein, wherein the pair of openings or recesses are in opposed radially extending relation to one another; and a trocar assembly release mechanism configured to releasably secure the trocar assembly within the outer tube, the release mechanism including: a pair of release buttons rotatably supported on opposed radial sides of the outer tube, wherein each release button is selectively receivable within a respective opening of the pair of openings or recesses formed in the trocar housing, each release button being movable between a release condition and an engaged condition; and a pair of biasing members supported in the outer tube and associated with a respective one of the pair of release buttons, wherein the biasing members urge the pair of release buttons to the engaged condition and into engagement with the trocar housing; a pair of release buttons rotatably supported on opposed radial sides of the outer tube, wherein each release button is selectively receivable within a respective opening of the pair of openings or recesses formed in the trocar housing, each release button being movable between a release condition and an engaged condition; and a pair of biasing members supported in the outer tube and associated with a respective one of the pair of release buttons, wherein the biasing members urge the pair of release buttons to the engaged condition and into engagement with the trocar housing; wherein, when the release buttons are in the engaged, locked condition, the release buttons are disposed within the pair of openings or recesses of the trocar housing to maintain the trocar assembly connected to the outer tube; and wherein, when the release buttons are in the release depressed, unlocked condition, the release buttons are disengaged from the pair of openings or recesses of the trocar housing to release the trocar assembly from the outer tube; each release button defines a proximal face projecting to a tail (1275a"), wherein when the trocar assembly is properly inserted into the outer tube, the release buttons are urged radially inward, to the locked condition, by the biasing members rotating the release buttons such that the tails thereof are received in the openings or recesses in the trocar housing to provide a visual indication to an end user that the trocar assembly is properly inserted into the outer tube and wherein when the trocar assembly is not properly inserted into the outer tube, the release buttons are urged radially outward, to the unlocked condition, to provide a visual indication to an end user that the trocar assembly is not properly inserted into the outer tube.