Usually, the reason for locking out tool probing is to prevent a collision and avoid damage to the machine or probe.
This can be done by the PLC and/or the probing cycle macro. You need to establish first which error you are getting, PLC or a program jump to an error line in the macro. If it's macro you could open and edit the probing cycle, or write a completely new macro allowing a tool probe where you want. However if it's PLC/NC, then you will have to return to A0.
A method many people use is to probe the tool length when called before use and again before putting it away. If excessive wear or tool break is found the tool is disabled. If a few microns wear is measured the tool length can be automatically updated if required.