Rule 23(1)(a) of the Uniform Rules of Court is peremptory and mandatory. Where a party intends to take an exception that a pleading is vague and embarrassing, that party must, by notice, afford the opposite party an opportunity to remove the cause of complaint before filing the exception. This requirement cannot be avoided by pleading the exception in the alternative (on the grounds that the pleading is vague and embarrassing and/or lacks necessary averments). The two grounds of exception - that a pleading is vague and embarrassing versus that it lacks necessary averments to sustain a defence - serve different legal functions and must be treated differently, with the former requiring strict compliance with the notice provisions of Rule 23(1)(a). An exception taken in violation of this mandatory requirement is irregular and must be dismissed. Special pleas of non-compliance with section 3 of Act 40 of 2002 and prescription are proper matters of law to be raised by way of special plea, and the appropriate response is replication under Rule 25, not exception.