Calibration errors in ABB robots typically occur when the robot's reference points or axis positions do not align with the expected or programmed values. This can be caused by various issues, including:

1. **Mechanical Misalignment**: If any of the robot's components, like the joints or gearboxes, are out of alignment due to wear or an external impact, calibration errors can occur.
2. **Encoder or Resolver Faults**: The robot uses encoders or resolvers to track joint positions. If these are malfunctioning or incorrectly calibrated, the robot's positioning will be inaccurate.
3. **Mastering Issues**: The mastering process establishes the robot's zero point for each axis. If the mastering is incorrect or not performed after a repair, calibration errors will show up.
4. **Battery Issues**: ABB robots often use backup batteries for encoders to retain position data when powered off. If the battery is low or dead, the position data might be lost, leading to errors when the robot is turned back on.
5. **Software Errors**: A corrupt software or configuration file may cause the system to misinterpret calibration data.

### Solutions:
1. **Re-master the robot**: Use the robot controller interface to re-master or recalibrate all axes.
2. **Check and replace encoders**: Inspect encoders for damage or malfunction and replace if necessary.
3. **Update or reflash the software**: Ensure the robot's software is up-to-date, or try reinstalling the current version to rule out software corruption.
4. **Inspect for mechanical issues**: Check for any signs of mechanical damage or misalignment and address them.
5. **Battery check**: Replace the backup battery if it's low to avoid losing position data during power-off states.