Unable to Program with PICkit™ 3 In-Circuit Debugger When Target is Very Close
You might be unable to program with the PICkit™ 3 In-Circuit Debugger when the target is very close to the connector. This may be due to ringing near the connector, which is not an uncommon occurrence with short traces. Add two 22 Ω resistors in series with the Programming Clock Lines (PGCs) and Programming Data Lines (PGDs) near the connector and this should attenuate the ringing.