The error you posted is commonly associated with broken third party plugins or behaviors, which we cannot fix, and does not actually contain much other useful information (the automatically provided information is pretty hit and miss). Without the actual project reproducing this problem, there is not sufficient evidence to consider this a bug in Construct 2. You can email the .capx to ashleyfyy@scirra.com if you would prefer not to share it publicly. Also note by design r151.2 removed the 'Load from JSON string' action and conflicting 'AsJSON' expression from the Array and Dictionary objects, since they overlapped features the objects already had; you might see this error if you used those features, in which case the workaround is to open in r151, delete those features and save, then reopen in r151.2.