SWD: Problems with 25 cm long tracks on PCB?

We want to programme our device without removing the PCB out of the housing. So we made pads on the PCB that can be reached from outside the housing. The distance between STM32F030C8T6 and the pads is about 25 cm.

Might this lengh be a problem for SWD lines? We sometimes have problems with hard fault. We have no galvanic separation from the of 230V line voltage, so we can not connect the debugger to see what happens.

With a PCB with cutted SWD lines the problem does not appear.