An image forming system including an image forming apparatus and a plurality of post processing apparatuses (120, 130, 140), the image forming system comprising: an abnormality detection unit (410, 510, 610) configured to detect a conveying abnormality of a recording material in a conveying path of the plurality of post processing apparatuses (120, 130, 140); a first determination unit, wherein in a case where the abnormality detection unit (120, 130, 140) detects the conveying abnormality of the recording material, the first determination unit is configured to determine, based on the number of recording material that are being conveyed in the image forming apparatus, whether there is any recording material that is being conveyed in the image forming apparatus and that cannot be stopped at a predetermined position defined so as to avoid a location that causes a deformation of the recording material; a second determination unit, wherein in a case where the first determination unit determines that there is a recording material that cannot be stopped at the predetermined position in the image forming apparatus, the second determination unit is configured to determine whether there is any post processing apparatus in which the recording material can be stopped at an upstream side with respect to the post processing apparatus where the conveying abnormality occurs; and a stop control unit (340, 440, 540), wherein in a case where the second determination unit determines that there is a post processing apparatus in which the recording material can be stopped, the stop control unit (340, 440, 540) is configured to discharge the recording material that cannot be stopped at the predetermined position in the image forming apparatus to a post processing apparatus at a downstream side with respect to the image forming apparatus and to stop the recording material in said post processing apparatus. an abnormality detection unit (410, 510, 610) configured to detect a conveying abnormality of a recording material in a conveying path of the plurality of post processing apparatuses (120, 130, 140); a first determination unit, wherein in a case where the abnormality detection unit (120, 130, 140) detects the conveying abnormality of the recording material, the first determination unit is configured to determine, based on the number of recording material that are being conveyed in the image forming apparatus, whether there is any recording material that is being conveyed in the image forming apparatus and that cannot be stopped at a predetermined position defined so as to avoid a location that causes a deformation of the recording material; a second determination unit, wherein in a case where the first determination unit determines that there is a recording material that cannot be stopped at the predetermined position in the image forming apparatus, the second determination unit is configured to determine whether there is any post processing apparatus in which the recording material can be stopped at an upstream side with respect to the post processing apparatus where the conveying abnormality occurs; and a stop control unit (340, 440, 540), wherein in a case where the second determination unit determines that there is a post processing apparatus in which the recording material can be stopped, the stop control unit (340, 440, 540) is configured to discharge the recording material that cannot be stopped at the predetermined position in the image forming apparatus to a post processing apparatus at a downstream side with respect to the image forming apparatus and to stop the recording material in said post processing apparatus.